Apple OS X 10.11 Security Technical Implementation Guide
| Version 1 Release 5 |
| 2017-07-28 |
| U_Apple_OS_X_10-11_STIG_V1R5_Manual-xccdf.xml |
| This Security Technical Implementation Guide is published as a tool to improve the security of Department of Defense (DoD) information systems. The requirements are derived from the National Institute of Standards and Technology (NIST) 800-53 and related documents. Comments or proposed revisions to this document should be sent via e-mail to the following address: disa.stig_spt@mail.mil. |
Vulnerabilities (118)
The operating system must conceal, via the session lock, information previously visible on the display with a publicly viewable image.
Discussion
A default screensaver must be configured for all users, as the screensaver will act as a session time-out lock for the system and must be one that conceals the contents of the screen from unauthorized users. The screensaver must not display any sensitive information or reveal the contents of the locked session screen. Publicly viewable images can include static or dynamic images such as patterns used with screen savers, photographic images, solid colors, a clock, a battery life indicator, or a blank screen.
Fix Text
This setting is enforced using the "Login Window Policy" configuration profile.
Check Content
To view the currently selected screen saver for the logged in user, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep moduleName If there is no result or defined "moduleName", this is a finding.
The operating system must initiate a session lock after a 15-minute period of inactivity.
Discussion
A screensaver must be enabled and set to require a password to unlock. The timeout should be set to fifteen minutes of inactivity. This mitigates the risk that a user might forget to manually lock the screen before stepping away from the computer. A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system, but does not log out because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, operating systems need to be able to identify when a user's session has idled and take action to initiate the session lock.
Fix Text
This setting is enforced using the "Login Window Policy" configuration profile.
Check Content
To check if the system has a configuration profile configured to enable the screen saver after a time-out period, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep idleTime The check should return a value of "900" or less for idleTime. If not, this is a finding.
The operating system must retain the session lock until the user reestablishes access using established identification and authentication procedures.
Discussion
Users must be prompted to enter their passwords when unlocking the screensaver. The screensaver acts as a session lock and prevents unauthorized users from accessing the current user's account.
Fix Text
This setting is enforced using the "Login Window Policy" configuration profile.
Check Content
To check if the system will prompt users to enter their passwords to unlock the screensaver, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep askForPassword If there is no result, or if "askForPassword" is not set to "1", this is a finding.
The operating system must monitor remote access methods.
Discussion
Remote access services, such as those providing remote access to network devices and information systems, increase risk and expose those systems to possible cyber attacks, so all remote access should be closely monitored and audited. Only authorized users should be permitted to remotely access DoD non-public information systems. An attacker might attempt to log in as an authorized user, through stolen credentials, unpatched exploits of the remote access service, or brute force attempts to guess a valid username and password. If a user is attempting to log in to a system from an unusual location or at an unusual time, or if there are many failed attempts, there is a possibility that the system is the target of a cyber attack. Auditing logon events mitigates this risk by recording all logon attempts, successful and unsuccessful, to the system.
Fix Text
To make sure the appropriate flags are enabled for auditing, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak '/^flags/ s/$/,lo/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the /etc/security/audit_control file.
Check Content
To check to make sure the audit daemon is configured to log all logon events, both local and remote, run the following command: /usr/bin/sudo /usr/bin/grep ^flags /etc/security/audit_control The flag "lo" should be included in the list of flags set. If it is not, this is a finding.
The operating system must, for networked systems, compare internal information system clocks at least every 24 hours with a server which is synchronized to one of the redundant United States Naval Observatory (USNO) time servers or a time server designated for the appropriate DoD network (NIPRNet/SIPRNet), and/or the Global Positioning System (GPS).
Discussion
Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside of the configured acceptable allowance (drift) may be inaccurate. Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Organizations should consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints).
Fix Text
To enable the "NTP" service, run the following command: /usr/bin/sudo /bin/launchctl load -w /System/Library/LaunchDaemons/org.ntp.ntpd.plist To configure one or more time servers for use, edit /etc/ntp.conf and enter each hostname or ip address on a separate line, prefixing each one with the keyword "server".
Check Content
The Network Time Protocol ("NTP") service must be enabled on all networked systems. To check if the service is running, use the following command: /usr/bin/sudo /bin/launchctl list | grep org.ntp.ntpd If nothing is returned, this is a finding. To ensure that an authorized NTP server is configured, run the following command or examine /etc/ntp.conf: /usr/bin/sudo /usr/bin/grep ^server /etc/ntp.conf Only approved time servers should be configured for use. If no server is configured, or if an unapproved time server is in use, this is a finding.
Audit log files must be owned by root.
Discussion
The audit service must be configured to create log files with the correct ownership to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log files are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log file that returns an incorrect owner, run the following command: /usr/bin/sudo chown root [audit log file] [audit log file] is the full path to the log file in question.
Check Content
To check the ownership of the audit log files, run the following command: /usr/bin/sudo ls -le $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') | grep -v current The results should show the owner (third column) to be "root". If not, this is a finding.
Audit log folders must be owned by root.
Discussion
The audit service must be configured to create log files with the correct ownership to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log files are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log folder that has an incorrect owner, run the following command: /usr/bin/sudo chown root [audit log folder]
Check Content
To check the ownership of the audit log folder, run the following command: /usr/bin/sudo ls -lde $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') The results should show the owner (third column) to be "root". If not, this is a finding.
Audit log files must be group-owned by wheel.
Discussion
The audit service must be configured to create log files with the correct group-ownership to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log files are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log file that returns an incorrect group-owner, run the following command: /usr/bin/sudo chgrp wheel [audit log file] [audit log file] is the full path to the log file in question.
Check Content
To check the group-ownership of the audit log files, run the following command: /usr/bin/sudo ls -le $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') | /usr/bin/grep -v current The results should show the group owner (fourth column) to be "wheel". If not, this is a finding.
Audit log folders must be group-owned by wheel.
Discussion
The audit service must be configured to create log files with the correct group-ownership to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log files are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log folder that has an incorrect group, run the following command: /usr/bin/sudo chgrp wheel [audit log folder]
Check Content
To check the group-ownership of the audit log folder, run the following command: /usr/bin/sudo ls -lde $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') The results should show the group (fourth column) to be "wheel", if not, this is a finding.
Audit log files must be mode 440 or less permissive.
Discussion
The audit service must be configured to create log files with the correct permissions to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log files are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log file that returns an incorrect permission value, run the following command: /usr/bin/sudo chmod 440 [audit log file] [audit log file] is the full path to the log file in question.
Check Content
To check the permissions of the audit log files, run the following command: /usr/bin/sudo ls -le $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') | /usr/bin/grep -v current The results should show the permissions (first column) to be "440" or less permissive, if not, this is a finding.
Audit log folders must have mode 700 or less permissive.
Discussion
The audit service must be configured to create log folders with the correct permissions to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log folders are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log folder that returns an incorrect permission value, run the following command: /usr/bin/sudo chmod 700 [audit log folder]
Check Content
To check the permissions of the audit log folder, run the following command: /usr/bin/sudo ls -lde $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') The results should show the permissions (first column) to be "700" or less permissive, if not, this is a finding.
Log files must not contain ACLs.
Discussion
The audit service must be configured to create log files with the correct permissions to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log files are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log file that contains ACLs, run the following command: /usr/bin/sudo chmod -N [audit log file]
Check Content
To check if a log file contains ACLs, run the following commands: /usr/bin/sudo ls -le $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') | /usr/bin/grep -v current In the output from the above commands, ACLs will be listed under any file that may contain them (e.g., "0: group:admin allow list,readattr,reaadextattr,readsecurity"). If any such line exists, this is a finding.
Log folders must not contain ACLs.
Discussion
The audit service must be configured to create log folders with the correct permissions to prevent normal users from reading audit logs. Audit logs contain sensitive data about the system and about users. If log folders are set to only be readable and writable by root or administrative users with sudo, the risk is mitigated.
Fix Text
For any log folder that contains ACLs, run the following command: /usr/bin/sudo chmod -N [audit log folder]
Check Content
To check if a log folder contains ACLs, run the following commands: /usr/bin/sudo ls -lde $(/usr/bin/sudo /usr/bin/grep '^dir' /etc/security/audit_control | awk -F: '{print $2}') In the output from the above commands, ACLs will be listed under any folder that may contain them (e.g., "0: group:admin allow list,readattr,reaadextattr,readsecurity"). If any such line exists, this is a finding.
The operating system must implement DoD-approved encryption to protect the confidentiality of remote access sessions.
Discussion
The rexec service must be disabled. The rexec service does not implement crypto and has had several security vulnerabilities in the past. It is disabled by default; enabling it would increase the attack surface of the system. Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DoD non-public information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Encryption provides a means to secure the remote connection to prevent unauthorized access to the data traversing the remote access connection (e.g., RDP) thereby providing a degree of confidentiality. The encryption strength of mechanism is selected based on the security categorization of the information.
Fix Text
To disable the "rexec" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.rexecd The system may need to be restarted for the update to take effect.
Check Content
To check if the "rexec" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.rexecd If the results do not show the following, this is a finding. "com.apple.rexecd" => true
The rshd service must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The "rshd" service must be disabled.
Fix Text
To disable the "rshd" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.rshd The system may need to be restarted for the update to take effect.
Check Content
To check if the "rshd" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.rshd If the results do not show the following, this is a finding. "com.apple.rshd" => true
The operating system must enforce requirements for remote connections to the information system.
Discussion
The Screen Sharing feature allows remote users to view or control the desktop of the current user. A malicious user can take advantage of screen sharing to gain full access to the system remotely, either with stolen credentials or by guessing the username and password. Disabling Screen Sharing mitigates this risk.
Fix Text
To disable the Screen Sharing service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.screensharing The system may need to be restarted for the update to take effect.
Check Content
To check if the Screen Sharing service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.screensharing If the results do not show the following, this is a finding. "com.apple.screensharing" => true
The Bluetooth software driver must be disabled.
Discussion
The Bluetooth kernel extension must be disabled, as wireless access introduces unnecessary security risks. Disabling Bluetooth support with a configuration profile mitigates this risk.
Fix Text
This setting is enforced using the "Bluetooth Policy" configuration profile.
Check Content
If Bluetooth connectivity is required to facilitate use of approved external devices, this is not applicable. To check if Bluetooth is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep DisableBluetooth If there is no result, or if "DisableBluetooth" is not set to "1", this is a finding.
Wi-Fi support software must be disabled.
Discussion
Use of Wi-Fi to connect to unauthorized networks may facilitate the exfiltration of mission data.
Fix Text
To disable the Wi-Fi network device, run the following command: /usr/bin/sudo /usr/sbin/networksetup -setnetworkserviceenabled "Wi-Fi" off
Check Content
If the system requires Wi-Fi to connect to an authorized network, this is not applicable. To check if the Wi-Fi network device is disabled, run the following command: /usr/bin/sudo /usr/sbin/networksetup -listallnetworkservices A disabled device will have an asterisk in front of its name. If the Wi-Fi device is missing this asterisk, this is a finding.
Infrared [IR] support must be disabled.
Discussion
Infrared [IR] kernel support must be disabled to prevent users from controlling the system with IR devices. By default, if IR is enabled, the system will accept IR control from any remote.
Fix Text
To disable IR, run the following command: /usr/bin/sudo /usr/bin/defaults write /Library/Preferences/com.apple.driver.AppleIRController DeviceEnabled -bool FALSE
Check Content
To check if IR support is disabled, run the following command: /usr/bin/sudo /usr/bin/defaults read /Library/Preferences/com.apple.driver.AppleIRController DeviceEnabled If the result is not "0", this is a finding.
Automatic actions must be disabled for blank CDs.
Discussion
Applications should not be configured to launch automatically when a disk is inserted. This potentially circumvents anti-virus software and allows malicious users to craft disks that can exploit user applications. Disabling Automatic Actions for blank CDs mitigates this risk.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
If an approved HBSS DCM/DLP solution is installed, this is not applicable. To check if the system has the correct setting for blank CDs in the configuration profile, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 2 'com.apple.digihub.blank.cd.appeared' If this is not defined or "action" is not set to "1", this is a finding.
Automatic actions must be disabled for blank DVDs.
Discussion
Applications should not be configured to launch automatically when a disk is inserted. This potentially circumvents anti-virus software and allows malicious users to craft disks that can exploit user applications. Disabling Automatic Actions for blank DVDs mitigates this risk.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
If an approved HBSS DCM/DLP solution is installed, this is not applicable. To check if the system has the correct setting for blank DVDs in the configuration profile, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 2 'com.apple.digihub.blank.dvd.appeared' If this is not defined or "action" is not set to "1", this is a finding.
Automatic actions must be disabled for music CDs.
Discussion
Applications should not be configured to launch automatically when a disk is inserted. This potentially circumvents anti-virus software and allows malicious users to craft disks that can exploit user applications. Disabling Automatic Actions for music CDs mitigates this risk.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
If an approved HBSS DCM/DLP solution is installed, this is not applicable. To check if the system has the correct setting for music CDs in the configuration profile, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 2 'com.apple.digihub.cd.music.appeared' If this is not defined or "action" is not set to "1", this is a finding.
Automatic actions must be disabled for picture CDs.
Discussion
Applications should not be configured to launch automatically when a disk is inserted. This potentially circumvents anti-virus software and allows malicious users to craft disks that can exploit user applications. Disabling Automatic Actions for picture CDs mitigates this risk.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
If an approved HBSS DCM/DLP solution is installed, this is not applicable. To check if the system has the correct setting for picture CDs in the configuration profile, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 2 'com.apple.digihub.cd.picture.appeared' If this is not defined or "action" is not set to "1", this is a finding.
Automatic actions must be disabled for video DVDs.
Discussion
Applications should not be configured to launch automatically when a disk is inserted. This potentially circumvents anti-virus software and allows malicious users to craft disks that can exploit user applications. Disabling Automatic Actions for video DVDs mitigates this risk.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
If an approved HBSS DCM/DLP solution is installed, this is not applicable. To check if the system has the correct setting for video DVDs in the configuration profile, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 2 'com.apple.digihub.dvd.video.appeared' If this is not defined or "action" is not set to "1", this is a finding.
The operating system must automatically remove or disable temporary user accounts after 72 hours.
Discussion
If temporary user accounts remain active when no longer needed or for an excessive period, these accounts may be targeted by attackers to gain unauthorized access. To mitigate this risk, automated termination of all temporary accounts must be set upon account creation. Temporary accounts are established as part of normal account activation procedures when there is a need for short-term accounts without the demand for immediacy in account activation. If temporary accounts are used, the operating system must be configured to automatically terminate these types of accounts after a DoD-defined time period of 72 hours. To address access requirements, many operating systems may be integrated with enterprise level authentication/access mechanisms that meet or exceed access control policy requirements.
Fix Text
This setting may be enforced using a configuration profile or by a directory server. To set the password policy without a configuration profile, run the following command to save a copy of the current policy file, substituting the correct user name in place of username: /usr/bin/sudo /usr/bin/pwpolicy -u username getaccountpolicies | tail -n +2 > pwpolicy.plist Open the resulting password policy file in a text editor. If other policy settings are present, and the line "<key>policyCategoryAuthentication</key>" already exists, insert the following text after the <array> tag that immediately follows it: <dict> <key>policyContent</key> <string>policyAttributeCurrentTime < policyAttributeCreationTime + 259299</string> <key>policyIdentifier</key> <string>Disable Temporary Account</string> </dict> At a minimum, edit the file to ensure that it contains the following text: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>policyCategoryAuthentication</key> <array> <dict> <key>policyContent</key> <string>policyAttributeCurrentTime < policyAttributeCreationTime + 259299</string> <key>policyIdentifier</key> <string>Disable Temporary Account</string> </dict> </array> </dict> </plist> After saving the file and exiting to the command prompt, run the following command to load the new policy file, substituting the correct user name in place of username: /usr/bin/sudo /usr/bin/pwpolicy -u username setaccountpolicies pwpolicy.plist
Check Content
Password policy can be set with the "pwpolicy" utility. The variable names may vary depending on how the policy was set. To check if the password policy is configured to disable a temporary account after 72 hours, run the following command to output the password policy to the screen, substituting the correct user name in place of username: /usr/bin/sudo /usr/bin/pwpolicy -u username getaccountpolicies | tail -n +2 If there is no output, and password policy is not controlled by a directory server, this is a finding. Otherwise, look for the line "<key>policyCategoryAuthentication</key>". In the array that follows, there should be a <dict> section that contains a check <string> that allows users to log in if "policyAttributeCurrentTime" is less than the result of adding "policyAttributeCreationTime" to 72 hours (259299 seconds). The check might use a variable defined in its "policyParameters" section. If the check does not exist or if the check adds too great an amount of time to "policyAttributeCreationTime", this is a finding.
The operating system must provide an immediate real-time alert to the SA and ISSO, at a minimum, of all audit failure events requiring real-time alerts.
Discussion
The audit service should be configured to immediately print messages to the console or email administrator users when an auditing failure occurs. It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without a real-time alert, security personnel may be unaware of an impending failure of the audit capability and system operation may be adversely affected.
Fix Text
To make "auditd" log errors to standard error as well as "syslogd", run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/logger -p/logger -s -p/' /etc/security/audit_warn; /usr/bin/sudo /usr/sbin/audit -s
Check Content
By default, "auditd" only logs errors to syslog. To see if audit has been configured to print error messages to the console, run the following command: /usr/bin/sudo /usr/bin/grep logger /etc/security/audit_warn If the argument "-s" is missing, or if audit_warn has not been otherwise modified to print errors to the console or send email alerts to the SA and ISSO, this is a finding.
The operating system must provide an immediate warning to the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75% of repository maximum audit record storage capacity.
Discussion
The audit service must be configured to require a minimum percentage of free disk space in order to run. This ensures that audit will notify the administrator that action is required to free up more disk space for audit logs. When minfree is set to 25%, security personnel are notified immediately when the storage volume is 75% full and are able to plan for audit record storage capacity expansion.
Fix Text
Edit the /etc/security/audit_control file, and change the value for "minfree" to "25". Use the following command to set the "minfree" value to "25%": /usr/bin/sudo /usr/bin/sed -i.bak 's/.*minfree.*/minfree:25/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the /etc/security/audit_control file.
Check Content
The check displays the "% free" to leave available for the system. The audit system will not write logs if the volume has less than this percentage of free disk space. To view the current setting, run the following command: /usr/bin/sudo /usr/bin/grep ^minfree /etc/security/audit_control If this returns no results, or does not contain "25", this is a finding.
The operating system must allocate audit record storage capacity to store at least one weeks worth of audit records, when audit records are not immediately sent to a central audit record storage facility.
Discussion
The audit service must be configured to require that records are kept for 7 days or longer before deletion when there is no central audit record storage facility. When "expire-after" is set to "7d", the audit service will not delete audit logs until the log data is at least 7 days old.
Fix Text
Edit the /etc/security/audit_control file, and change the value for 'expire-after' to the amount of time audit logs should be kept for the system. Use the following command to set the "expire-after" value to "7d": /usr/bin/sudo /usr/bin/sed -i.bak 's/.*expire-after.*/expire-after:7d/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the /etc/security/audit_control file.
Check Content
The check displays the amount of time the audit system is configured to retain audit log files. The audit system will not delete logs until the specified condition has been met. To view the current setting, run the following command: /usr/bin/sudo /usr/bin/grep ^expire-after /etc/security/audit_control If this returns no results, or does not contain "7d" or a larger value, this is a finding.
The operating system must be configured such that emergency administrator accounts are never automatically disabled.
Discussion
Emergency administrator accounts are privileged accounts which are established in response to crisis situations where the need for rapid account activation is required. Therefore, emergency account activation may bypass normal account authorization processes. If these accounts are automatically disabled, system maintenance during emergencies may not be possible, thus adversely affecting system availability. Emergency administrator accounts are different from infrequently used accounts (i.e., local logon accounts used by system administrators when network or normal logon/access is not available). Infrequently used accounts also remain available and are not subject to automatic termination dates. However, an emergency administrator account is normally a different account which is created for use by vendors or system maintainers. To address access requirements, many operating systems can be integrated with enterprise-level authentication/access mechanisms that meet or exceed access control policy requirements.
Fix Text
To remove all pwpolicy settings for an emergency account, run the following command, replacing username with the correct value: /usr/bin/sudo /usr/bin/pwpolicy -u username clearaccountpolicies Otherwise, to change the password policy for an emergency account and only remove some policy sections, run the following command to save a copy of the current policy file for the specified username: /usr/bin/sudo /usr/bin/pwpolicy -u username getaccountpolicies | tail -n +2 > pwpolicy.plist Open the resulting password policy file in a text editor and remove any policyContent sections that would restrict the ability to log on after a certain date or amount of time. To remove the section cleanly, remove the entire text that begins with <dict>, contains the like <key>policyContent<'/key>, and ends with </dict>. After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy -u username setaccountpolicies pwpolicy.plist
Check Content
If an emergency account has been created on the system, check the expiration settings of a local account using the following command, replacing username with the correct value: /usr/bin/sudo /usr/bin/pwpolicy -u username getaccountpolicies | tail -n +2 If there is output, ensure that the account policies do not restrict the ability to log on after a certain date or amount of time, if they do, this is a finding.
The operating system must generate audit records for all account creations, modifications, disabling, and termination events, for privileged activities or other system-level access, all kernel module load, unload, and restart actions, all program initiations, and organizationally defined events for all non-local maintenance and diagnostic sessions.
Discussion
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000327-GPOS-00127, SRG-OS-000392-GPOS-00172, SRG-OS-000471-GPOS-00215, SRG-OS-000471-GPOS-00216, SRG-OS-000476-GPOS-00221, SRG-OS-000477-GPOS-00222
Fix Text
To make sure the appropriate flags are enabled for auditing, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak '/^flags/ s/$/,ad/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the "/etc/security/audit_control" file.
Check Content
In order to view the currently configured flags for the audit daemon, run the following command: /usr/bin/sudo /usr/bin/grep ^flags /etc/security/audit_control If "ad" is not listed in the result of the check, this is a finding.
SMB File Sharing must be disabled unless required.
Discussion
File Sharing is usually non-essential and must be disabled if not required. Enabling any service increases the attack surface for an intruder. By disabling unnecessary services, the attack surface is minimized.
Fix Text
To disable the SMB File Sharing service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.smbd The system may need to be restarted for the update to take effect.
Check Content
If SMB File Sharing is required, this is not applicable. To check if the SMB File Sharing service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.smbd If the results do not show the following, this is a finding. "com.apple.smbd" => true
Apple File (AFP) Sharing must be disabled.
Discussion
File Sharing is non-essential and must be disabled. Enabling any service increases the attack surface for an intruder. By disabling unnecessary services, the attack surface is minimized.
Fix Text
To disable the Apple File (AFP) Sharing service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.AppleFileServer The system may need to be restarted for the update to take effect.
Check Content
To check if the Apple File (AFP) Sharing service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.AppleFileServer If the results do not show the following, this is a finding. "com.apple.AppleFileServer" => true
The NFS daemon must be disabled unless required.
Discussion
If the system does not require access to NFS (Network File System) file shares or is not acting as an NFS server, then support for NFS is non-essential and NFS services must be disabled. NFS is a network file system protocol supported by Unix-like operating systems. Enabling any service increases the attack surface for an intruder. By disabling unnecessary services, the attack surface is minimized.
Fix Text
To disable the NFS daemon, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.nfsd The system may need to be restarted for the update to take effect.
Check Content
If the NFS daemon is required, this is not applicable. To check if the NFS daemon is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.nfsd If the results do not show the following, this is a finding. "com.apple.nfsd" => true
The NFS lock daemon must be disabled unless required.
Discussion
If the system does not require access to NFS (Network File System) file shares or is not acting as an NFS server, then support for NFS is non-essential and NFS services must be disabled. NFS is a network file system protocol supported by Unix-like operating systems. Enabling any service increases the attack surface for an intruder. By disabling unnecessary services, the attack surface is minimized.
Fix Text
To disable the NFS lock daemon, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.lockd The system may need to be restarted for the update to take effect.
Check Content
If the NFS lock daemon is required, this is not applicable. To check if the NFS lock daemon is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.lockd If the results do not show the following, this is a finding. "com.apple.lockd" => true
The NFS stat daemon must be disabled unless required.
Discussion
If the system does not require access to NFS (Network File System) file shares or is not acting as an NFS server, then support for NFS is non-essential and NFS services must be disabled. NFS is a network file system protocol supported by Unix-like operating systems. Enabling any service increases the attack surface for an intruder. By disabling unnecessary services, the attack surface is minimized.
Fix Text
To disable the NFS stat daemon, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.statd.notify The system may need to be restarted for the update to take effect.
Check Content
If the NFS stat daemon is required, this is not applicable. To check if the NFS stat daemon is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.statd.notify If the results do not show the following, this is a finding. "com.apple.statd.notify" => true
The system firewall must be configured with a default-deny policy.
Discussion
An approved firewall must be installed and enabled to work in concert with the OS X Application Firewall. When configured correctly, firewalls protect computers from network attacks by blocking or limiting access to open network ports.
Fix Text
Install an approved HBSS or firewall solution onto the system and configure it with a "default-deny" policy.
Check Content
The system firewall must be configured with a "default-deny" policy. Ask the SA or ISSO if an approved firewall is loaded on the system. The recommended system is the McAfee HBSS. If there is no firewall installed on the system, this is a finding. If there is a firewall installed and it is not configured with a "default-deny" policy, this is a finding.
The SSH banner must contain the Standard Mandatory DoD Notice and Consent Banner.
Discussion
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. The banner must be formatted in accordance with DTM-08-060.
Fix Text
For systems that allow remote access through SSH, create a plain text file containing the required text and save it as /etc/banner.
Check Content
For systems that allow remote access through SSH, run the following command to ensure that /etc/banner exists: /bin/ls -l /etc/banner If /etc/banner does not exist, this is a finding. The banner text of the document MUST read: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." If the text is not worded exactly this way, this is a finding.
The operating system must initiate session audits at system startup.
Discussion
If auditing is enabled late in the startup process, the actions of some start-up processes may not be audited. Some audit systems also maintain state information only available if auditing is enabled before a given process is created.
Fix Text
To enable the audit service, run the following command: /usr/bin/sudo /bin/launchctl load -w /System/Library/LaunchDaemons/com.apple.auditd.plist
Check Content
To check if the audit service is running, use the following command: /usr/bin/sudo /bin/launchctl list | /usr/bin/grep com.apple.auditd If nothing is returned, the audit service is not running, this is a finding.
The operating system must generate audit records for DoD defined events such as: successful/unsuccessful logon attempts, successful/unsuccessful direct access attempts, starting and ending time for user access, and concurrent logons to the same account from different sources.
Discussion
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Satisfies: SRG-OS-000470-GPOS-00214, SRG-OS-000472-GPOS-00217, SRG-OS-000473-GPOS-00218, SRG-OS-000475-GPOS-00220
Fix Text
To make sure the appropriate flags are enabled for auditing, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak '/^flags/ s/$/,aa/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the "/etc/security/audit_control" file.
Check Content
In order to view the currently configured flags for the audit daemon, run the following command: /usr/bin/sudo /usr/bin/grep ^flags /etc/security/audit_control Logon events are logged by way of the "aa" flag. If "aa" is not listed in the result of the check, this is a finding.
Any connection to the operating system must display the Standard Mandatory DoD Notice and Consent Banner before granting access to the system.
Discussion
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. The banner must be formatted in accordance with DTM-08-060. Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088
Fix Text
Create a RTF formatted file containing the required text. Name the file "PolicyBanner.rtf" or "PolicyBanner.rtfd" and place it in /Library/Security/
Check Content
The policy banner will show if a "PolicyBanner.rtf" or "PolicyBanner.rtfd" exists in the /Library/Security folder. Run this command to show the contents of that folder: /bin/ls -l /Library/Security/PolicyBanner.rtf* If neither "PolicyBanner.rtf" nor "PolicyBanner.rtfd" exists, this is a finding. The banner text of the document MUST read: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." If the text is not worded exactly this way, this is a finding.
The operating system must display the Standard Mandatory DoD Notice and Consent Banner before granting access to the system via SSH.
Discussion
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. The banner must be formatted in accordance with DTM-08-060.
Fix Text
For systems that allow remote access through SSH, modify the /etc/ssh/sshd_config file to add or update the following line: Banner /etc/banner
Check Content
For systems that allow remote access through SSH, run the following command to ensure that /etc/banner is displayed before granting access: # /usr/bin/grep Banner /etc/ssh/sshd_config If the sshd Banner configuration option does not point to "/etc/banner", this is a finding.
The Security assessment policy subsystem must be enabled.
Discussion
Any changes to the hardware, software, and/or firmware components of the information system and/or application can potentially have significant effects on the overall security of the system. Accordingly, software defined by the organization as critical software must be signed with a certificate that is recognized and approved by the organization.
Fix Text
To enable the Security assessment policy subsystem, run the following command: /usr/bin/sudo /usr/sbin/spctl --master-enable
Check Content
To check the status of the Security assessment policy subsystem, run the following command: /usr/bin/sudo /usr/sbin/spctl --status | /usr/bin/grep enabled If nothing is returned, this is a finding.
The operating system must limit privileges to change software resident within software libraries.
Discussion
File permissions should be compared against the default set of permissions that were set at the time of the initial install. Changes to default file permissions can make the system less secure and disrupt the functionality of installed applications. Unless changes are required to harden a system, the default permissions should be kept. If the operating system were to allow any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. Verifying that permissions remain unchanged mitigates this risk. This requirement applies to operating systems with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs which execute with escalated privileges. Only qualified and authorized individuals shall be allowed to obtain access to information system components for purposes of initiating changes, including upgrades and modifications.
Fix Text
To re-enable "System Integrity Protection", boot the affected system into "Recovery" Mode, launch "Terminal" from the "Utilities" menu, and run the following command: /usr/bin/csrutil enable
Check Content
System Integrity Protection is a security feature, enabled by default, that protects certain system processes and files from being modified or tampered with. The current status of "System Integrity Protection" can be checked with the following command: /usr/bin/csrutil status If the result does not show the following, this is a finding. System Integrity Protection status: enabled.
A configuration profile must be installed.
Discussion
Configuration settings must be verified by a centrally managed system such as an MDM to ensure that they have not been changed. Configuration settings are the configurable security-related parameters of information technology products that are part of the information system. Security-related parameters are those parameters impacting the security state of the system including parameters related to meeting other security control requirements. Rather than visiting each and every system when verifying configuration changes, organizations will employ automated tools that can make changes across all systems. This greatly increases efficiency and manageability of applications in a large scale environment.
Fix Text
Obtain a configuration profile from an MDM or trusted provider containing the configuration settings required to be applied.
Check Content
To check if the system has a configuration profile applied, run the following command: sudo /usr/bin/profiles -H If there are no profiles installed, this is a finding.
The operating system must employ a deny-all, permit-by-exception policy to allow the execution of authorized software programs.
Discussion
Application Restrictions must be enabled for user accounts and configured to only allow users to execute approved applications. Utilizing a whitelist such as Application Restrictions provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities. The organization must identify authorized software programs and permit execution of authorized software. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as whitelisting.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. Built-in applications such as "FaceTime", "Game Center", "Mail", "Contacts", "Calendar", "Reminders", "Notes", and "Messages" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application FaceTime must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application FaceTime establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "FaceTime" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = FaceTime;" If anything is returned, this is a finding. Built-in applications such as "FaceTime" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application Game Center must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Game Center establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Game Center" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "GKFeatureGameCenterAllowed = 0;" If nothing is returned, this is a finding.
The application Messages must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Messages establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Messages" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = Messages;" If anything is returned, this is a finding. Built-in applications such as "Messages" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application Calendar must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Calendar establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Calendar" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = Calendar;" If anything is returned, this is a finding. Built-in applications such as "Calendar" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application Reminders must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Reminders establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Reminders" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = Reminders;" If anything is returned, this is a finding. Built-in applications such as "Reminders" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application Contacts must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Contacts establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Contacts" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = Contacts;" If anything is returned, this is a finding. Built-in applications such as "Contacts" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application Mail must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Mail establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Mail" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = Mail;" If anything is returned, this is a finding. Built-in applications such as "Mail" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The application Notes must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The application Notes establishes connections to Apple's iCloud, despite using security controls to disable iCloud access.
Fix Text
This setting is enforced using the "Applications Restrictions Policy" configuration profile.
Check Content
To check if there is a configuration policy defined for "Application Restrictions", run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "familyControlsEnabled = 1;" If nothing is returned, this is a finding. To check if "Notes" is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep "displayName = Notes;" If anything is returned, this is a finding. Built-in applications such as "Notes" should be evaluated against mission needs and should only appear in the list of allowed applications if specifically required.
The system preference panels iCloud and Internet Accounts must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The system preference panel's iCloud and Internet Accounts must be disabled.
Fix Text
This setting is enforced using the "Restrictions Policy" configuration profile.
Check Content
Access to the "iCloud" and "Internet Accounts" preference panes must be disabled. To check if the system has the correct setting in the configuration profile, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 5 'DisabledPreferencePanes' If nothing is returned, this is a finding. To check if "iCloud" has been disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep com.apple.preferences.icloud If nothing is returned, this is a finding. To check if "Internet Accounts" has been disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep com.apple.preferences.internetaccounts If nothing is returned, this is a finding.
Sending diagnostic and usage data to Apple must be disabled.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Sending diagnostic and usage data to Apple must be disabled.
Fix Text
This setting is enforced using the "Security Privacy Policy" configuration profile. The setting "Send diagnostic & usage data to Apple" is found in System Preferences >> Security & Privacy >> Privacy >> Diagnostics & Usage. Uncheck the box that says "Send diagnostic & usage data to Apple." To apply the setting from the command line, run the following commands: /usr/bin/defaults read "/Library/Application Support/CrashReporter/DiagnosticMessagesHistory.plist" AutoSubmit /usr/bin/sudo /usr/bin/defaults write "/Library/Application Support/CrashReporter/DiagnosticMessagesHistory.plist" AutoSubmit -bool false /usr/bin/sudo /bin/chmod 644 /Library/Application\ Support/CrashReporter/DiagnosticMessagesHistory.plist /usr/bin/sudo /usr/bin/chgrp admin /Library/Application\ Support/CrashReporter/DiagnosticMessagesHistory.plist
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"Sending diagnostic & usage data to Apple" must be disabled. To check if a configuration profile is configured to enforce this setting, run the following command: /usr/bin/sudo /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep AutoSubmit If "AutoSubmit" is not set to "0", this is a finding. Alternately, the setting is found in System Preferences >> Security & Privacy >> Privacy >> Diagnostics & Usage. If the box that says "Send diagnostic & usage data to Apple" is checked, this is a finding.
Find My Mac must be disabled.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Find My Mac must be disabled.
Fix Text
To disable the "Find My Mac" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.findmymacd The system may need to be restarted for the update to take effect.
Check Content
To check if the "Find My Mac" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.findmymacd If the results do not show the following, this is a finding. "com.apple.findmymacd" => true
Find My Mac messenger must be disabled.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Find My Mac messenger must be disabled.
Fix Text
To disable the "Find My Mac messenger" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.findmymacmessenger The system may need to be restarted for the update to take effect.
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To check if the "Find My Mac messenger" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.findmymacmessenger If the results do not show the following, this is a finding. "com.apple.findmymacmessenger" => true
Location Services must be disabled.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Location Services must be disabled.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile. The setting "Enable Location Services" can be found in System Preferences >> Security & Privacy >> Privacy >> Location Services. Uncheck the box that says "Enable Location Services". It can also be set with the following command: /usr/bin/sudo /usr/bin/defaults write /private/var/db/locationd/Library/Preferences/ByHost/com.apple.locationd.`/usr/sbin/system_profiler SPHardwareDataType | /usr/bin/grep "Hardware UUID" | /usr/bin/cut -c22-57` LocationServicesEnabled -bool false
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"Location Services" must be disabled. To check if a configuration profile is configured to enforce this setting, run the following command: /usr/bin/sudo /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep DisableLocationServices If "DisableLocationServices" is not set to "1", this is a finding. The setting is found in System Preferences >> Security & Privacy >> Privacy >> Location Services. If the box that says "Enable Location Services" is checked, this is a finding. To check if the setting was applied on the command line, run the following command: /usr/bin/sudo /usr/bin/defaults read /private/var/db/locationd/Library/Preferences/ByHost/com.apple.locationd.`/usr/sbin/system_profiler SPHardwareDataType | /usr/bin/grep "Hardware UUID" | /usr/bin/cut -c22-57` LocationServicesEnabled
Bonjour multicast advertising must be disabled on the system.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Bonjour multicast advertising must be disabled on the system.
Fix Text
To configure Bonjour to disable multicast advertising, run the following command: /usr/bin/sudo /usr/bin/defaults write /Library/Preferences/com.apple.mDNSResponder.plist NoMulticastAdvertisements -bool true The system will need to be restarted for the update to take effect.
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Bonjour multicast advertising must be disabled on the system. To check if multicast advertisements have been disabled, run the following command: /usr/bin/sudo /usr/bin/defaults read /Library/Preferences/com.apple.mDNSResponder | /usr/bin/grep NoMulticastAdvertisements If there is an error returned, or nothing returned, or "NoMulticastAdvertisements" is not set to "1", this is a finding.
The UUCP service must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. The system must not have the UUCP service active.
Fix Text
To disable the "UUCP" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.uucp The system may need to be restarted for the update to take effect.
Check Content
To check if the "UUCP" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.uucp If the results do not show the following, this is a finding. "com.apple.uucp" => true
The operating system must require individuals to be authenticated with an individual authenticator prior to using a group authenticator.
Discussion
Administrator users must never log in directly as root. To assure individual accountability and prevent unauthorized access, logging in as root over a remote connection must be disabled. Administrators should only run commands as root after first authenticating with their individual user names and passwords.
Fix Text
In order to make sure that "PermitRootLogin" is disabled by sshd, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/^[\#]*PermitRootLogin.*/PermitRootLogin no/' /etc/ssh/sshd_config
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To check if SSH has "PermitRootLogin" enabled, run the following command: /usr/bin/sudo /usr/bin/grep ^PermitRootLogin /etc/ssh/sshd_config If there is no result, or the result is set to "yes", this is a finding.
The operating system must implement replay-resistant authentication mechanisms for network access to privileged and non-privileged accounts.
Discussion
The SSH Version should be explicitly set to Version 2. Version 2 supports strong crypto and was rewritten from scratch to resolve several weaknesses in Version 1 that make it extremely vulnerable to attackers. The weaker crypto in Version 1 is potentially susceptible to certain forms of replay attacks. The system default is to only enable Version 2. A replay attack may enable an unauthorized user to gain access to the operating system. Authentication sessions between the authenticator and the operating system validating the user credentials must not be vulnerable to a replay attack. An authentication process resists replay attacks if it is impractical to achieve a successful authentication by recording and replaying a previous authentication message. Satisfies: SRG-OS-000112-GPOS-00057, SRG-OS-000113-GPOS-00058
Fix Text
In order to make sure that "Protocol 2" is used by sshd, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.*Protocol.*/Protocol 2/' /etc/ssh/sshd_config
Check Content
To check which protocol is configured for sshd, run the following: /usr/bin/sudo /usr/bin/grep ^Protocol /etc/ssh/sshd_config If there is no result or the result is not "2", this is a finding.
Operating systems must enforce password complexity by requiring that at least one numeric character be used.
Discussion
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determine how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server. To set the password policy without a configuration profile, run the following command to save a copy of the current pwpolicy account policy file: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies | tail -n +2 > pwpolicy.plist Open the generated file in a text editor. If the file does not yet contain any policy settings, replace <dict/> with <dict></dict>. Then, insert the following text after the opening <dict> tag and before the closing </dict> tag. The same text can also be used if the line "<key>policyCategoryPasswordContent</key>" is not present. <key>policyCategoryPasswordContent</key> <array> <dict> <key>policyContent</key> <string>policyAttributePassword matches '(.*[0-9].*){1,}+'</string> <key>policyIdentifier</key> <string>com.apple.policy.legacy.requiresNumeric</string> <key>policyParameters</key> <dict> <key>minimumNumericCharacters</key> <integer>1</integer> </dict> </dict> </array> If the file does contain policy settings, and the line "<key>policyCategoryPasswordContent</key>" does exist, insert the following text after the opening <array> tag that comes right after it: <dict> <key>policyContent</key> <string>policyAttributePassword matches '(.*[0-9].*){1,}+'</string> <key>policyIdentifier</key> <string>com.apple.policy.legacy.requiresNumeric</string> <key>policyParameters</key> <dict> <key>minimumNumericCharacters</key> <integer>1</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration may block password change and local user creation operations, as well as, lock out all local users, including administrators.
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Password policy can be set with a configuration profile or the "pwpolicy" utility. If password policy is set with a configuration profile, run the following command to check if the system is configured to require that passwords contain at least one numeric character: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep requireAlphanumeric If "requireAlphanumeric" is not set to "1" or is undefined, this is a finding. If password policy is set with the "pwpolicy utility", run the following command instead: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies Look for the line "<key>policyCategoryPasswordContent</key>". If it does not exist, and password policy is not controlled by a directory server, this is a finding. Otherwise, in the array section that follows it, there should be a <dict> section that contains a check <string> that "matches" the variable "policyAttributePassword" to the regular expression "(.*[0-9].*){1,}+" or to a similar expression that will ensure the password contains a character in the range 0-9 one or more times. If this check allows users to create passwords without at least one numeric character, or if no such check exists, this is a finding.
The operating system must enforce password complexity by requiring that at least one special character be used.
Discussion
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity or strength is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor in determining how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Special characters are those characters that are not alphanumeric. Examples include: ~ ! @ # $ % ^ *.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server.
Check Content
Password policy can be set with a configuration profile or the pwpolicy utility. If password policy is set with a configuration profile, run the following command to check if the system is configured to require that passwords contain at least one special character: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep minComplexChars If "minComplexChars" is not set to "1" or is undefined, this is a finding. Run the following command to check if the system is configured to require that passwords not contain of repeated sequential characters or characters in increasing and decreasing sequential order: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep allowSimple If "allowSimple" is not set to "0" or is undefined, this is a finding.
The operating system must enforce a minimum 15-character password length.
Discussion
The minimum password length must be set to 15 characters. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. The use of more characters in a password helps to exponentially increase the time and/or resources required to compromise the password.
Fix Text
This setting is enforced using the "Passcode Policy" configuration profile. Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration may block password change and local user creation operations, as well as, lock out all local users, including administrators.
Check Content
To check the currently applied policies for password and accounts, use the following command: /usr/bin/sudo /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep minLength The parameter minLength should be "15". If it is less than "15", this is a finding.
The operating system must implement cryptography to protect the integrity and confidentiality of data during transmission of remote access sessions, non-local maintenance sessions, and diagnostic communications.
Discussion
The "telnet" service must be disabled as it sends all data in a clear text form that can be easily intercepted and read. The data needs to be protected at all times during transmission and encryption is the standard method for protecting data in transit. If the data is not encrypted during transmission, it can be plainly read (i.e., clear text) and easily compromised. Disabling telnet is one way to mitigate this risk. Administrators should be instructed to use an alternate service for remote access sessions, non-local maintenance sessions, and diagnostic communications that uses encryption, such as SSH. Satisfies: SRG-OS-000074-GPOS-00042, SRG-OS-000125-GPOS-00065, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174
Fix Text
To disable the "telnet" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.telnetd The system may need to be restarted for the update to take effect.
Check Content
To check if the "telnet" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.telnetd If the results do not show the following, this is a finding. "com.apple.telnetd" => true
The system must allow only applications downloaded from the App Store to run.
Discussion
Gatekeeper settings must be configured correctly to only allow the system to run applications downloaded from the Mac App Store or applications signed with a valid Apple Developer ID code. Administrator users will still have the option to override these settings on a per app basis. Gatekeeper is a security feature that ensures that applications must be digitally signed by an Apple issued certificate in order to run. Digital signatures allow the OS X to verify that the application has not been modified by a malicious third-party.
Fix Text
This setting is enforced using the "Security Privacy Policy" configuration profile.
Check Content
To check to make sure only applications downloaded from the App Store are allowed to run, type the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep EnableAssessment If "EnableAssessment" is not set to "1", this is a finding. /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep AllowIdentifiedDevelopers If "AllowIdentifiedDevelopers" is not set to "1", this is a finding.
End users must not be able to override Gatekeeper settings.
Discussion
"Gatekeeper" must be configured with a configuration profile in order to prevent normal users from overriding its setting. If users are allowed to disable Gatekeeper or set it to a less restrictive setting, then it is possible that malware could be introduced into the system. Gatekeeper is a security feature that ensures that applications must be digitally signed by an Apple issued certificate in order to run. Digital signatures allow Mac OS X to verify that the application has not been modified by a malicious third-party.
Fix Text
This setting is enforced using the "Security Privacy Policy" configuration profile.
Check Content
To check to make sure the user cannot override "Gatekeeper" settings, type the following code: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep DisableOverride If "DisableOverride" is not set to "1", this is a finding.
The SSH daemon ClientAliveInterval option must be set correctly.
Discussion
SSH should be configured to log users out after a "15" minute interval of inactivity and to only wait "30" seconds before timing out login attempts. Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session or an incomplete login attempt will also free up resources committed by the managed network element.
Fix Text
In order to make sure that "ClientAliveInterval" is set correctly, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.*ClientAliveInterval.*/ClientAliveInterval 600/' /etc/ssh/sshd_config
Check Content
The SSH daemon "ClientAliveInterval" option must be set correctly. To check the idle timeout setting for SSH sessions, run the following: /usr/bin/sudo /usr/bin/grep ^ClientAliveInterval /etc/ssh/sshd_config If the setting is not "600", this is a finding.
The SSH daemon ClientAliveCountMax option must be set correctly.
Discussion
SSH should be configured to log users out after a "15" minute interval of inactivity and to only wait "30" seconds before timing out login attempts. Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session or an incomplete login attempt will also free up resources committed by the managed network element.
Fix Text
In order to make sure that the SSH idle timeout occurs precisely when the "ClientAliveCountMax" is set, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.*ClientAliveCountMax.*/ClientAliveCountMax 0/' /etc/ssh/sshd_config
Check Content
The SSH daemon "ClientAliveCountMax" option must be set correctly. To ensure the SSH idle timeout will occur when the "ClientAliveCountMax" is set, run the following command: /usr/bin/sudo /usr/bin/grep ^ClientAliveCountMax /etc/ssh/sshd_config If the setting is not "ClientAliveCountMax 0", this is a finding.
The operating system must audit the enforcement actions used to restrict access associated with changes to the system.
Discussion
By auditing access restriction enforcement, changes to application and OS configuration files can be audited. Without auditing the enforcement of access restrictions, it will be difficult to identify attempted attacks and an audit trail will not be available for forensic investigation. Enforcement actions are the methods or mechanisms used to prevent unauthorized changes to configuration settings. Enforcement action methods may be as simple as denying access to a file based on the application of file permissions (access restriction). Audit items may consist of lists of actions blocked by access restrictions or changes identified after the fact.
Fix Text
To set the audit flags to the recommended setting, run the following command to add the flags "fm", "-fr", and "-fw" all at once: /usr/bin/sudo /usr/bin/sed -i.bak '/^flags/ s/$/,fm,-fr,-fw/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the "/etc/security/audit_control" file.
Check Content
In order to view the currently configured flags for the audit daemon, run the following command: /usr/bin/sudo /usr/bin/grep ^flags /etc/security/audit_control Enforcement actions are logged by way of the "fm" flag, which audits permission changes, and "-fr" and "-fw", which denote failed attempts to read or write to a file. If "fm", "-fr", and "-fw" are not listed in the result of the check, this is a finding.
ACLs for system log files must be set correctly.
Discussion
System logs should only be readable by root or admin users. System logs frequently contain sensitive information that could be used by an attacker. Setting the correct ACLs mitigates this risk.
Fix Text
For any log file that returns an ACL, run the following command: /usr/bin/sudo chmod -N [log file] [log file] is the full path to the log file in question.
Check Content
These commands check for log files that exist on the system and print out the list of ACLs if there are any. /usr/bin/sudo ls -ld@ $(/usr/bin/grep -v '^#' /etc/newsyslog.conf | awk '{ print $1 }') 2> /dev/null /usr/bin/sudo ls -ld@ $(/usr/bin/grep -e '^>' /etc/asl.conf /etc/asl/* | awk '{ print $2 }') 2> /dev/null ACLs will be listed under any file that may contain them, i.e., "0: group:admin allow list,readattr,reaadextattr,readsecurity". If any system log file contains this information, this is a finding.
System log files must be mode 640 or less permissive.
Discussion
System logs should only be readable by root or admin users. System logs frequently contain sensitive information that could be used by an attacker. Setting the correct permissions mitigates this risk.
Fix Text
For any log file that returns an incorrect permission value, run the following command: /usr/bin/sudo chmod 640 [log file] [log file] is the full path to the log file in question. If the file is managed by "newsyslog", find the configuration line in the directory "/etc/newsyslog.d/" or the file "/etc/newsyslog.conf" and edit the mode column to be "640" or less permissive. If the file is managed by "aslmanager", find the configuration line in the directory "/etc/asl/" or the file "/etc/asl.conf" and add or edit the mode option to be "mode=0640" or less permissive.
Check Content
These commands check for log files that exist on the system and print out the log with corresponding permissions. Run them from inside "/var/log": /usr/bin/sudo stat -f '%A:%N' $(/usr/bin/grep -v '^#' /etc/newsyslog.conf | awk '{ print $1 }') 2> /dev/null /usr/bin/sudo stat -f '%A:%N' $(/usr/bin/grep -e '^>' /etc/asl.conf /etc/asl/* | awk '{ print $2 }') 2> /dev/null The correct permissions on log files should be "640" or less permissive for system logs. Any file with more permissive settings is a finding.
System log files must be owned by root and group-owned by wheel or admin.
Discussion
System logs should only be readable by root or admin users. System logs frequently contain sensitive information that could be used by an attacker. Setting the correct owner mitigates this risk.
Fix Text
For any log file that returns an incorrect owner or group value, run the following command: /usr/bin/sudo chown root:wheel [log file] [log file] is the full path to the log file in question. If the file is managed by "newsyslog", find the configuration line in the directory "/etc/newsyslog.d/" or the file "/etc/newsyslog.conf" and ensure that the owner:group column is set to "root:wheel" or the appropriate service user account and group. If the file is managed by "aslmanager", find the configuration line in the directory "/etc/asl/" or the file "/etc/asl.conf" and ensure that "uid" and "gid" options are either not present or are set to a service user account and group respectively.
Check Content
Log files are controlled by "newsyslog" and "aslmanager". These commands check for log files that exist on the system and print out the log with corresponding ownership. Run them from inside "/var/log": /usr/bin/sudo stat -f '%Su:%Sg:%N' $(/usr/bin/grep -v '^#' /etc/newsyslog.conf | awk '{ print $1 }') 2> /dev/null /usr/bin/sudo stat -f '%Su:%Sg:%N' $(/usr/bin/grep -e '^>' /etc/asl.conf /etc/asl/* | awk '{ print $2 }') 2> /dev/null If there are any system log files that are not owned by "root" and group-owned by "wheel" or admin, this is a finding. Service logs may be owned by the service user account or group.
The operating system must generate audit records when successful/unsuccessful attempts to access/modify privileges occur.
Discussion
Frequently, an attacker that successfully gains access to a system has only gained access to an account with limited privileges, such as a guest account or a service account. The attacker must attempt to change to another user account with normal or elevated privileges in order to proceed. Auditing successful and unsuccessful attempts to switch to another user account and the escalation of privileges mitigates this risk. Satisfies: SRG-OS-000064-GPOS-00033, SRG-OS-000462-GPOS-00206
Fix Text
To make sure the appropriate flags are enabled for auditing, run the following command: /usr/bin/sudo sed -i.bak '/^flags/ s/$/,lo/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the "/etc/security/audit_control" file.
Check Content
In order to view the currently configured flags for the audit daemon, run the following command: /usr/bin/sudo /usr/bin/grep ^flags /etc/security/audit_control If "lo" is not listed in the result of the check, this is a finding.
The operating system must prohibit password reuse for a minimum of five generations.
Discussion
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. If the information system or application allows the user to consecutively reuse their password when that password has exceeded its defined lifetime, the end result is a password that is not changed as per policy requirements.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server. To set the password policy without a configuration profile, run the following command to save a copy of the current "pwpolicy" account policy file: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies | tail -n +2 > pwpolicy.plist Open the generated file in a text editor. If the file does not yet contain any policy settings, replace <dict/> with <dict></dict>. If there already is a policy block that refers to password history, ensure it is set to "5". If the line "<key>policyCategoryPasswordContent</key>" is not present in the file, add the following text immediately after the opening <dict> tag in the file: <key>policyCategoryPasswordContent</key> <array> <dict> <key>policyContent</key> <string>none policyAttributePasswordHashes in policyAttributePasswordHistory</string> <key>policyIdentifier</key> <string>Password History</string> <key>policyParameters</key> <dict> <key>policyAttributePasswordHistoryDepth</key> <integer>5</integer> </dict> </dict> </array> If the line "<key>policyCategoryPasswordContent</key>" is already present in the file, the following text should be added just after the opening <array> tag that follows the line instead: <dict> <key>policyContent</key> <string>none policyAttributePasswordHashes in policyAttributePasswordHistory</string> <key>policyIdentifier</key> <string>Password History</string> <key>policyParameters</key> <dict> <key>policyAttributePasswordHistoryDepth</key> <integer>5</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration may block password change and local user creation operations, as well as, lock out all local users, including administrators.
Check Content
Password policy can be set with the "Passcode Policy" configuration profile or the "pwpolicy" utility. If password policy is set with a configuration profile, run the following command to check if the system is configured to require that users cannot reuse one of their five previously used passwords: system_profiler SPConfigurationProfileDataType | /usr/bin/grep pinHistory If "pinHistory" is not set to "5" or higher, or is undefined, this is a finding. If password policy is set with the "pwpolicy" utility, run the following command instead: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies Look for the line "<key>policyCategoryPasswordContent</key>". If it does not exist, and password policy is not controlled by a directory server, this is a finding. Otherwise, in the array section that follows it, there should be a <dict> section that contains a check <string> such as "<string>none policyAttributePasswordHashes in policyAttributePasswordHistory</string>". This searches for the hash of the user-entered password in the list of previous password hashes. In the "policyParameters" section that follows it, "policyAttributePasswordHistoryDepth" must be set to "5" or greater. If this parameter is not set to "5" or greater, or if no such check exists, this is a finding.
Operating systems must enforce a 60-day maximum password lifetime restriction.
Discussion
Any password, no matter how complex, can eventually be cracked. Therefore, passwords need to be changed periodically. One method of minimizing this risk is to use complex passwords and periodically change them. If the operating system does not limit the lifetime of passwords and force users to change their passwords, there is the risk that the operating system passwords could be compromised.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server. To set the password policy without a configuration profile, run the following command to save a copy of the current "pwpolicy" account policy file: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies | tail -n +2 > pwpolicy.plist Open the generated file in a text editor. If the file does not yet contain any policy settings, replace <dict/> with <dict></dict>. If there already is a policy block that refers to password expiration, ensure it is set to "60" days. If the line "<key>policyCategoryPasswordChange</key>" is not present in the file, add the following text immediately after the opening <dict> tag in the file: <key>policyCategoryPasswordChange</key> <array> <dict> <key>policyContent</key> <string>policyAttributeCurrentTime > policyAttributeLastPasswordChangeTime + (policyAttributeExpiresEveryNDays * 24 * 60 * 60)</string> <key>policyIdentifier</key> <string>Password Change Interval</string> <key>policyParameters</key> <dict> <key>policyAttributeExpiresEveryNDays</key> <integer>60</integer> </dict> </dict> </array> If the line "<key>policyCategoryPasswordChange</key>" is already present in the file, the following text should be added just after the opening <array> tag that follows the line instead: <dict> <key>policyContent</key> <string>policyAttributeCurrentTime > policyAttributeLastPasswordChangeTime + (policyAttributeExpiresEveryNDays * 24 * 60 * 60)</string> <key>policyIdentifier</key> <string>Password Change Interval</string> <key>policyParameters</key> <dict> <key>policyAttributeExpiresEveryNDays</key> <integer>60</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration may block password change and local user creation operations, as well as, lock out all local users, including administrators.
Check Content
Password policy can be set with a configuration profile or the "pwpolicy" utility. If password policy is set with a configuration profile, run the following command to check if the system is configured to require users to change their passwords every 60 days: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep maxPINAgeInDays If "maxPINAgeInDays" is not set to "60" or a shorter interval, or is undefined, this is a finding. If password policy is set with the "pwpolicy" utility, run the following command instead: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies Look for the line <key>policyCategoryPasswordChange</key>. If it does not exist, and password policy is not controlled by a directory server, this is a finding. Otherwise, in the array section that follows it, there should be a <dict> section that contains a check <string> that compares the variable "policyAttributeLastPasswordChangeTime" to the variable "policyAttributeCurrentTime". It may contain additional variables defined in the "policyParameters" section that follows it. All comparisons are done in seconds. If this check allows users to log in with passwords older than "60" days, or if no such check exists, this is a finding.
The system must be integrated into a directory services infrastructure.
Discussion
Distinct user account databases on each separate system cause problems with username and password policy enforcement. Most approved directory services infrastructure solutions allow centralized management of users and passwords.
Fix Text
Integrate the system into an existing directory services infrastructure.
Check Content
To determine if the system is integrated to a directory server, ask the SA or ISSO or run the following command: /usr/bin/sudo dscl localhost -list . | /usr/bin/grep -vE '(Contact | Search | Local)' If nothing is returned, or if the system is not integrated into a directory service infrastructure, this is a finding.
All users must use PKI authentication for login and privileged access.
Discussion
Password-based authentication has become a prime target for malicious actors. Multifactor authentication using PKI technologies mitigates most, if not all, risks associated with traditional password use. (Use of username and password for last-resort emergency access to a system for maintenance is acceptable, however.)
Fix Text
Implement PKI authentication using approved third-party PKI tools, to integrate with an existing directory services infrastructure or local password database, where no directory services infrastructure exists.
Check Content
Ask the SA or ISSO if an approved PKI authentication solution is implemented on the system for user logins and privileged access. If an account can log in to the system or gain privileged access without a smart card, and it is not an emergency account, this is a finding.
AirDrop must be disabled.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. AirDrop must be disabled.
Fix Text
Disabling "AirDrop" is enforced using the "Restrictions Policy" configuration profile.
Check Content
"AirDrop" must be disabled. To check if "AirDrop" has been disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep DisableAirDrop If "DisableAirDrop" is not set to "1", this is a finding.
The SSH daemon LoginGraceTime must be set correctly.
Discussion
SSH should be configured to log users out after a 15 minute interval of inactivity and to only wait 30 seconds before timing out login attempts. Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session or an incomplete login attempt will also free up resources committed by the managed network element.
Fix Text
In order to make sure that "LoginGraceTime" is configured correctly, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.*LoginGraceTime.*/LoginGraceTime 30/' /etc/ssh/sshd_config
Check Content
The SSH daemon "LoginGraceTime" must be set correctly. To check the amount of time that a user can login through SSH, run the following command: /usr/bin/sudo /usr/bin/grep ^LoginGraceTime /etc/ssh/sshd_config If the value is not set to "30" or less, this is a finding.
The operating system must issue or obtain public key certificates under an appropriate certificate policy from an approved service provider.
Discussion
DoD-approved certificates must be installed to the System Keychain so that they will be available to all users. For user certificates, each organization attains certificates from an approved, shared service provider, as required by OMB policy. For federal agencies operating a legacy public key infrastructure cross-certified with the Federal Bridge Certification Authority at medium assurance or higher, this Certification Authority will suffice. This control focuses on certificates with a visibility external to the information system and does not include certificates related to internal system operations, for example, application-specific time services.
Fix Text
Obtain the approved DOD certificates from the appropriate authority. Use Keychain Access from /Applications/Utilities to add certificates to the System keychain.
Check Content
To view a list of installed certificates, run the following command: /usr/bin/sudo /usr/bin/security dump-keychain | /usr/bin/grep labl | awk -F\" '{ print $4 }' If this list does not contain approved certificates, this is a finding.
The operating system must implement cryptographic mechanisms to protect the confidentiality and integrity of all information at rest.
Discussion
Information at rest refers to the state of information when it is located on a secondary storage device (e.g., disk drive and tape drive) within an organizational information system. Mobile devices, laptops, desktops, and storage devices can be either lost or stolen, and the contents of their data storage (e.g., hard drives and non-volatile memory) can be read, copied, or altered. By encrypting the system hard drive, the confidentiality and integrity of any data stored on the system is ensured. FileVault Disk Encryption mitigates this risk. Satisfies: SRG-OS-000185-GPOS-00079, SRG-OS-000404-GPOS-00183, SRG-OS-000405-GPOS-00184
Fix Text
Open System Preferences >> Security and Privacy, and navigate to the "FileVault" tab. Use this panel to configure full-disk encryption. Alternately, from the command line, run the following command to enable "FileVault": /usr/bin/sudo /usr/bin/fdesetup enable After "FileVault" is initially set up, additional users can be added.
Check Content
To check if "FileVault 2" is enabled, run the following command: /usr/bin/sudo /usr/bin/fdesetup status If "FileVault" is "Off" and the device is a laptop, this is a finding.
The operating system must employ automated mechanisms to determine the state of system components with regard to flaw remediation using the following frequency: continuously, where HBSS is used; 30 days, for any additional internal network scans not covered by HBSS; and annually, for external scans by Computer Network Defense Service Provider (CNDSP).
Discussion
An approved tool for continuous network scanning must be installed and configured to run. Without the use of automated mechanisms to scan for security flaws on a continuous and/or periodic basis, the operating system or other system components may remain vulnerable to the exploits presented by undetected software flaws. To support this requirement, the operating system may have an integrated solution incorporating continuous scanning using HBSS and periodic scanning using other tools, as specified in the requirement.
Fix Text
Install an approved HBSS solution onto the system.
Check Content
Ask the SA or ISSO if an approved tool capable of continuous scanning is loaded on the system. The recommended system is the McAfee HBSS. If no such tool is installed on the system, this is a finding.
The operating system must restrict the ability of individuals to use USB storage devices.
Discussion
External hard drives, such as USB, must be disabled for users. USB hard drives are a potential vector for malware and can be used to exfiltrate sensitive data, if an approved data-loss prevention (DLP) solution is not installed.
Fix Text
This setting is enforced using the "Restrictions Policy" configuration profile.
Check Content
If an approved HBSS DCM/DLP solution is installed, this is not applicable. To ensure external USB drives are disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 3 harddisk-external If the option "eject,alert" is not set for "harddisk-external", this is a finding.
The usbmuxd daemon must be disabled.
Discussion
Connections to unauthorized iOS devices (iPhones, iPods, and iPads) open the system to possible compromise via exfiltration of system data. Disabling the usbmuxd daemon blocks connections to iOS devices.
Fix Text
To disable the "usbmuxd" daemon, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.usbmuxd The system may need to be restarted for the update to take effect.
Check Content
If the system is approved for management of iOS devices, this is not applicable. To check if the "usbmuxd" daemon is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.usbmuxd If the results do not show the following, this is a finding. "com.apple.usbmuxd" => true
The operating system must automatically lock the account until the locked account is released by an administrator when three unsuccessful logon attempts in 15 minutes are exceeded.
Discussion
By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute forcing, is reduced. Limits are imposed by locking the account. Setting a lockout expiration of 15 minutes is an effective deterrent against brute forcing that also makes allowances for legitimate mistakes by users.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server. To set the password policy without a configuration profile, run the following command to save a copy of the current "pwpolicy" account policy file: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies | tail -n +2 > pwpolicy.plist Open the generated file in a text editor and ensure it contains the following text after the opening <dict> tag and before the closing </dict> tag. Replace <dict/> first with <dict></dict> if necessary. <key>policyCategoryAuthentication</key> <array> <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> </array> If the line "<key>policyCategoryAuthentication</key>" already exists, the following text should be used instead and inserted after the first <array> tag that follows it: <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration or bugs in OS X may block password change and local user creation operations, as well as, lock out all local users, including administrators.
Check Content
Password policy can be set with a configuration profile or the "pwpolicy" utility. If password policy is set with a configuration profile, run the following command to check if the system has the correct setting for the number of permitted failed logon attempts and the logon reset timer: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep 'maxFailedAttempts\|minutesUntilFailedLoginReset' If "maxFailedAttempts" is not set to "3" and "minutesUntilFailedLoginReset" is not set to "15", this is a finding. If password policy is set with the "pwpolicy" utility, the variable names may vary depending on how the policy was set. To check if the password policy is configured to disable an account for 15 minutes after 3 unsuccessful logon attempts, run the following command to output the password policy to the screen: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies Look for the line "<key>policyCategoryAuthentication</key>". If this does not exist, and password policy is not controlled by a directory server, this is a finding. In the array that follows, there should be one or more <dict> sections that describe policy checks. One should contain a <string> that allows users to log on if "policyAttributeFailedAuthentications" is less than "policyAttributeMaximumFailedAuthentications". Under policyParameters, "policyAttributeMaximumFailedAuthentications" should be set to "3". If "policyAttributeMaximumFailedAuthentications" is not set to "3", this is a finding. In the same check or in another <dict> section, there should be a <string> that allows users to log on if the "policyAttributeCurrentTime" is greater than the result of adding "15" minutes (900 seconds) to "policyAttributeLastFailedAuthenticationTime". The check might use a variable defined in its "policyParameters" section. If the check does not exist or if the check adds too great an amount of time, this is a finding.
The operating system must shut down by default upon audit failure (unless availability is an overriding concern).
Discussion
The audit service should shut down the computer if it is unable to audit system events. Once audit failure occurs, user and system activity is no longer recorded and malicious activity could go undetected. Audit processing failures include: software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode. When availability is an overriding concern, other approved actions in response to an audit failure are as follows: (i) If the failure was caused by the lack of audit record storage capacity, the operating system must continue generating audit records if possible (automatically restarting the audit service if necessary), overwriting the oldest audit records in a first-in-first-out manner. (ii) If audit records are sent to a centralized collection server and communication with this server is lost or the server fails, the operating system must queue audit records locally until communication is restored or until the audit records are retrieved manually. Upon restoration of the connection to the centralized collection server, action should be taken to synchronize the local audit data with the collection server.
Fix Text
Edit the "/etc/security/audit_control file", and change the value for policy to include the setting "ahlt". To programmatically do this, run the following command: sudo /usr/bin/sed -i.bak '/^policy/ s/$/,ahlt/' /etc/security/audit_control; sudo /usr/sbin/audit -s
Check Content
To view the setting for the audit control system, run the following command: sudo /usr/bin/grep ^policy /etc/security/audit_control | /usr/bin/grep ahlt If there is no result, this is a finding.
The operating system must not allow an unattended or automatic logon to the system.
Discussion
When automatic logins are enabled, the default user account is automatically logged in at boot time without prompting the user for a password. Even if the screen is later locked, a malicious user would be able to reboot the computer in order to log in. Disabling automatic logins mitigates this risk.
Fix Text
This setting is enforced using the "Login Window Policy" configuration profile.
Check Content
To check if the system is configured to automatically log on, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep DisableAutoLoginClient If "com.apple.login.mcx.DisableAutoLoginClient" is not set to "1", this is a finding.
The login window must be configured to prompt for username and password, rather than show a list of users.
Discussion
The login window must be configured to prompt all users for both a username and a password. By default, the system displays a list of known users at the login screen. This gives an advantage to an attacker with physical access to the system, as the attacker would only have to guess the password for one of the listed accounts.
Fix Text
This setting is enforced using the "Login Window Policy" configuration profile.
Check Content
To check if the login window is configured to prompt for user name and password, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep SHOWFULLNAME If there is no result, or "SHOWFULLNAME" is not set to "1", this is a finding.
The OS X firewall must have logging enabled.
Discussion
Firewall logging must be enabled. This ensures that malicious network activity will be logged to the system.
Fix Text
To enable the firewall logging, run the following command: /usr/bin/sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setloggingmode on
Check Content
If HBSS is used, this is not applicable. To check if the OS X firewall has logging enabled, run the following command: /usr/libexec/ApplicationFirewall/socketfilterfw --getloggingmode | /usr/bin/grep on If the result does not show "on", this is a finding.
Bluetooth devices must not be allowed to wake the computer.
Discussion
Bluetooth devices must not be allowed to wake the computer. If Bluetooth is not required, turn it off. If Bluetooth is necessary, disable allowing Bluetooth devices to wake the computer.
Fix Text
This control needs to be manually changed on the computer by opening System Preferences >> Bluetooth, Click Advanced, and make sure the "Allow Bluetooth devices to wake this computer" is not checked. This control is not necessary if Bluetooth has been completely disabled. The following can be run from the command line to disable "Remote Wake" for the current user: /usr/bin/defaults write /Users/`whoami`/Library/Preferences/ByHost/com.apple.Bluetooth.`/usr/sbin/system_profiler SPHardwareDataType | /usr/bin/grep "Hardware UUID" | /usr/bin/cut -c22-57`.plist RemoteWakeEnabled 0
Check Content
To check if this setting is disabled run the following two commands as the primary user: /usr/bin/defaults -currentHost read com.apple.Bluetooth RemoteWakeEnabled /usr/bin/defaults read /Users/`whoami`/Library/Preferences/ByHost/com.apple.Bluetooth.`/usr/sbin/system_profiler SPHardwareDataType | grep "Hardware UUID" | cut -c22-57`.plist RemoteWakeEnabled If there is an error or nothing is returned, or the return value is "1" for either command, this is a finding.
Bluetooth Sharing must be disabled.
Discussion
Bluetooth sharing allows users to wirelessly transmit files between the OS X and Bluetooth-enabled devices, including personally owned cell phones and tablets. A malicious user might introduce viruses or malware onto the system or extract sensitive files. Disabling Bluetooth Sharing mitigates this risk.
Fix Text
To disable Bluetooth Sharing, open System Preferences >> Sharing and uncheck the box next to "Bluetooth Sharing". This control is not necessary if Bluetooth has been completely disabled. The following can be run from the command line to disable "Bluetooth Sharing" for the current user: /usr/bin/defaults write /Users/`whoami`/Library/Preferences/ByHost/com.apple.Bluetooth.`/usr/sbin/system_profiler SPHardwareDataType | /usr/bin/grep "Hardware UUID" | /usr/bin/cut -c22-57`.plist PrefKeyServicesEnabled 0
Check Content
To check if Bluetooth Sharing is enabled, open up System Preferences >> Sharing and verify that "Bluetooth Sharing" is not checked "ON". If it is "ON", this is a finding. The following command can be run from the command line: /usr/bin/defaults read /Users/`whoami`/Library/Preferences/ByHost/com.apple.Bluetooth.`/usr/sbin/system_profiler SPHardwareDataType | grep "Hardware UUID" | cut -c22-57`.plist PrefKeyServicesEnabled If there is an error or nothing is returned, or the return value is "1", this is a finding.
Remote Apple Events must be disabled.
Discussion
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, games, software packages, tools, and demonstration software, not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled. Remote Apple Events must be disabled.
Fix Text
To disable the "Remote Apple Events" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.AEServer The system may need to be restarted for the update to take effect.
Check Content
To check if the "Remote Apple Events" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.AEServer If the results do not show the following, this is a finding. "com.apple.AEServer" => true
The sudoers file must be configured to authenticate users on a per-tty basis.
Discussion
The sudo command must be configured to prompt for the administrator user's password at least once in each newly opened Terminal window or remote login session, as this prevents a malicious user from taking advantage of an unlocked computer or an abandoned login session to bypass the normal password prompt requirement. Without the tty_tickets option, all open local and remote logon sessions would be authenticated to use sudo without a password for the duration of the configured password timeout window.
Fix Text
Edit the "/etc/sudoers" file to contain the line: Defaults tty_tickets This line can be placed in the defaults section or at the end of the file.
Check Content
To check if the "tty_tickets" option is set for "/usr/bin/sudo", run the following command: /usr/bin/sudo /usr/bin/grep tty_tickets /etc/sudoers If there is no result, this is a finding.
The application firewall must be enabled.
Discussion
The Application Firewall is the built-in firewall that comes with the OS X and must be enabled. Firewalls protect computers from network attacks by blocking or limiting access to open network ports. Application firewalls limit which applications are allowed to communicate over the network.
Fix Text
To enable the firewall run the following command: /usr/bin/sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on
Check Content
If an approved HBSS solution is installed, this is not applicable. To check if the OS X firewall has been enabled, run the following command: /usr/bin/sudo /usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate If the result is "disabled", this is a finding.
All public directories must be owned by root or an application account.
Discussion
All public directories must be owned by root, the local admin user, or an application account. Directory owners have permission to delete any files contained in that directory, even if the files are owned by other user accounts. By setting the owner to an administrator or application account, regular users will not be permitted to delete each other's files.
Fix Text
To change the ownership of any finding, run the following command: /usr/bin/sudo find / -type d -perm +o+w -not -uid 0 -exec chown root {} \;
Check Content
To display all directories that are writable by all and not owned by "root", run the following command: /usr/bin/sudo find / -type d -perm +o+w -not -uid 0 If anything is returned, and those directories are not owned by a local admin or application account, this is a finding.
The finger service must be disabled.
Discussion
The finger service has had several security vulnerabilities in the past and is not a necessary service. It is disabled by default; enabling it would increase the attack surface of the system.
Fix Text
To disable the "finger" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/com.apple.fingerd The system may need to be restarted for the update to take effect.
Check Content
To check if the "finger" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep com.apple.fingerd If the results do not show the following, this is a finding. "com.apple.fingerd" => true
The sticky bit must be set on all public directories.
Discussion
The sticky bit must be set on all public directories, as it prevents users with write access to the directory from deleting or renaming files that belong to other users inside it.
Fix Text
Run the following command to set the "sticky bit" on all world-writable directories: /usr/bin/sudo /usr/bin/find / -type d \( -perm -0002 -a ! -perm -1000 \) -exec chmod +t {} \;
Check Content
Run the following command to view all world-writable directories that do not have the "sticky bit" set: /usr/bin/sudo /usr/bin/find / -type d \( -perm -0002 -a ! -perm -1000 \) If anything is returned, this is a finding.
The prompt for Apple ID and iCloud must be disabled.
Discussion
The prompt for Apple ID and iCloud must be disabled, as it might mislead new users into creating unwanted Apple IDs and iCloud storage accounts upon their first log on.
Fix Text
This setting is enforced using the "Disable iCloud Policy" configuration profile.
Check Content
To check if the prompt for "Apple ID" and "iCloud" are disabled for new users, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep SkipCloudSetup If "SkipCloudSetup" is not set to "1", this is a finding.
Users must not have Apple IDs signed into iCloud.
Discussion
Users should not sign into iCloud, as this leads to the possibility that sensitive data could be saved to iCloud storage or that users could inadvertently introduce viruses or malware previously saved to iCloud from other systems.
Fix Text
This must be manually resolved. With the affected user logged in, open System Preferences >> iCloud. Choose "Sign Out".
Check Content
To see if any user account has configured an Apple ID for iCloud usage, run the following command: /usr/bin/sudo find /Users/ -name 'MobileMeAccounts.plist' -exec /usr/bin/defaults read '{}' \; If the results show any accounts listed, this is a finding.
iTunes Music Sharing must be disabled.
Discussion
When iTunes Music Sharing is enabled, the computer starts a network listening service that shares the contents of the user's music collection with other users in the same subnet. Unnecessary network services should always be disabled because they increase the attack surface of the system. Disabling iTunes Music Sharing mitigates this risk.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
To check if the iTunes music sharing is disabled, run the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep disableSharedMusic If "disableSharedMusic" is not set to "1", this is a finding.
All setuid executables on the system must be vendor-supplied.
Discussion
Very few of the executables that come preinstalled on the OS X have the setuid bit set, and administrators should never add the setuid bit to any executable that does not already have it set by the vendor. Executables with the setuid bit set allow anyone that executes them to be temporarily assigned the UID of the file owner. In practice, this almost always is the root account. While some vendors depend on this file attribute for proper operation, security problems can result if setuid is assigned to programs allowing reading and writing of files, or shell escapes, as this could lead to unprivileged users gaining privileged access to files and directories on the system.
Fix Text
Document all of the files with the "setuid" bit set. Remove any undocumented files.
Check Content
If available, provide a list of setuids provided by a vendor. To list all of the files with the "setuid" bit set, run the following command to send all results to a file named "suidfilelist": /usr/bin/sudo find / -perm -4000 -exec /bin/ls -ldb {} \; > suidfilelist If any of the files listed are not documented as needing to have the "setuid" bit set by the vendor, this is a finding.
The system must not accept source-routed IPv4 packets.
Discussion
A source-routed packet attempts to specify the network path the packet should take. If the system is not configured to block the incoming source-routed packets, an attacker can redirect the system's network traffic. Configuring the system to drop incoming source-routed IPv4 packets mitigates this risk.
Fix Text
To configure the system to not accept "source-routed" packets, add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.ip.accept_sourceroute=0
Check Content
To check if the system is configured to accept "source-routed" packets, run the following command: sysctl net.inet.ip.accept_sourceroute If the value is not "0", this is a finding.
The system must ignore IPv4 ICMP redirect messages.
Discussion
ICMP redirects are broadcast in order to reshape network traffic. A malicious user could craft fake redirect packets and try to force all network traffic to pass through a network sniffer. If the system is not configured to ignore these packets, it could be susceptible to this kind of attack.
Fix Text
To configure the system to ignore "ICMP redirect" messages, add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.icmp.drop_redirect=1
Check Content
To check if the system is configured to ignore "ICMP redirect" messages, run the following command: sysctl net.inet.icmp.drop_redirect If the value is not "1", this is a finding.
IP forwarding for IPv4 must not be enabled.
Discussion
IP forwarding for IPv4 must not be enabled, as only authorized systems should be permitted to operate as routers.
Fix Text
To configure the system to disable "IP forwarding", add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.ip.forwarding=0
Check Content
To check if "IP forwarding" is enabled, run the following command: sysctl net.inet.ip.forwarding If the values are not "0", this is a finding.
IP forwarding for IPv6 must not be enabled.
Discussion
IP forwarding for IPv6 must not be enabled, as only authorized systems should be permitted to operate as routers.
Fix Text
To configure the system to disable "IP forwarding", add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet6.ip6.forwarding=0
Check Content
To check if "IP forwarding" is enabled, run the following command: sysctl net.inet6.ip6.forwarding If the values are not "0", this is a finding.
The operating system must enforce account lockout after the limit of three consecutive invalid logon attempts by a user during a 15 minute time period.
Discussion
By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute forcing, is reduced. Limits are imposed by locking the account.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server. To set the password policy without a configuration profile, run the following command to save a copy of the current "pwpolicy" account policy file: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies | tail -n +2 > pwpolicy.plist Open the generated file in a text editor and ensure it contains the following text after the opening <dict> tag and before the closing </dict> tag. Replace <dict/> first with <dict></dict> if necessary. <key>policyCategoryAuthentication</key> <array> <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> </array> If the line "<key>policyCategoryAuthentication</key>" already exists, the following text should be used instead and inserted after the first <array> tag that follows it: <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist <key>policyCategoryAuthentication</key> <array> <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> </array> If the line <key>policyCategoryAuthentication</key> already exists, the following text should be used instead and inserted after the first <array> tag that follows it: <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration or bugs in OS X may block password change and local user creation operations, as well as, lock out all local users, including administrators.
Check Content
Password policy can be set with a configuration profile or the "pwpolicy" utility. If password policy is set with a configuration profile, run the following command to check if the system has the correct setting for the number of permitted failed logon attempts: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep 'maxFailedAttempts' If "maxFailedAttempts" is not set to "3", this is a finding. If password policy is set with the "pwpolicy" utility, the variable names may vary depending on how the policy was set. To check if the password policy is configured to disable an account for 15 minutes after 3 unsuccessful logon attempts, run the following command to output the password policy to the screen: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies Look for the line "<key>policyCategoryAuthentication</key>". If this does not exist, and password policy is not controlled by a directory server, this is a finding. In the array that follows, there should one or more <dict> sections that describe policy checks. One should contain a <string> that allows users to log on if "policyAttributeFailedAuthentications" is less than "policyAttributeMaximumFailedAuthentications". Under policyParameters, "policyAttributeMaximumFailedAuthentications" should be set to "3". If "policyAttributeMaximumFailedAuthentications" is not set to "3", this is a finding. In the same check or in another <dict> section, there should be a <string> that allows users to log on if the "policyAttributeCurrentTime" is greater than the result of adding "15" minutes (900 seconds) to "policyAttributeLastFailedAuthenticationTime". The check might use a variable defined in its policyParameters section. If the check does not exist or if the check adds too great an amount of time, this is a finding.
The operating system must enforce an account lockout time period of 15 minutes in which three consecutive invalid logon attempts by a user are made.
Discussion
Setting a lockout time period of 15 minutes is an effective deterrent against brute forcing that also makes allowances for legitimate mistakes by users. When three invalid logon attempts are made, the account will be locked.
Fix Text
This setting may be enforced using the "Passcode Policy" configuration profile or by a directory server. The following two lines within the configuration enforce lockout expiration to "15" minutes: <key>autoEnableInSeconds</key> <integer>900</integer> To set the password policy without a configuration profile, run the following command to save a copy of the current "pwpolicy" account policy file: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies | tail -n +2 > pwpolicy.plist Open the generated file in a text editor and ensure it contains the following text after the opening <dict> tag and before the closing </dict> tag. Replace <dict/> first with <dict></dict> if necessary. <key>policyCategoryAuthentication</key> <array> <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> </array> If the line "<key>policyCategoryAuthentication</key>" already exists, the following text should be used instead and inserted after the first <array> tag that follows it: <dict> <key>policyContent</key> <string>(policyAttributeFailedAuthentications < policyAttributeMaximumFailedAuthentications) OR (policyAttributeCurrentTime > (policyAttributeLastFailedAuthenticationTime + autoEnableInSeconds))</string> <key>policyIdentifier</key> <string>Authentication Lockout</string> <key>policyParameters</key> <dict> <key>autoEnableInSeconds</key> <integer>900</integer> <key>policyAttributeMaximumFailedAuthentications</key> <integer>3</integer> </dict> </dict> After saving the file and exiting to the command prompt, run the following command to load the new policy file: /usr/bin/sudo /usr/bin/pwpolicy setaccountpolicies pwpolicy.plist Note: Updates to password restrictions must be thoroughly evaluated in a test environment. Mistakes in configuration may block password change and local user creation operations, as well as, lock out all local users, including administrators.
Check Content
Password policy can be set with a configuration profile or the pwpolicy utility. If password policy is set with a configuration profile, run the following command to check if the system has the correct setting for the logon reset timer: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep 'minutesUntilFailedLoginReset' If "minutesUntilFailedLoginReset" is not set to "15", this is a finding. If password policy is set with the pwpolicy utility, the variable names may vary depending on how the policy was set. To check if the password policy is configured to disable an account for 15 minutes after 3 unsuccessful logon attempts, run the following command to output the password policy to the screen: /usr/bin/sudo /usr/bin/pwpolicy getaccountpolicies Look for the line "<key>policyCategoryAuthentication</key>". If this does not exist, and password policy is not controlled by a directory server, this is a finding. In the array that follows, there should one or more <dict> sections that describe policy checks. One should contain a <string> that allows users to log on if "policyAttributeFailedAuthentications" is less than "policyAttributeMaximumFailedAuthentications". Under policyParameters, "policyAttributeMaximumFailedAuthentications" should be set to "3". If "policyAttributeMaximumFailedAuthentications" is not set to "3", this is a finding. In the same check or in another <dict> section, there should be a <string> that allows users to log on if the "policyAttributeCurrentTime" is greater than the result of adding "15" minutes (900 seconds) to "policyAttributeLastFailedAuthenticationTime". The check might use a variable defined in its "policyParameters section". If the check does not exist or if the check adds too great an amount of time, this is a finding.
Web Sharing must be disabled.
Discussion
Web Sharing is non-essential and must be disabled. Enabling any service increases the attack surface for an intruder. By disabling unnecessary services, the attack surface is minimized.
Fix Text
To disable the "Web Sharing" service, run the following command: /usr/bin/sudo /bin/launchctl disable system/org.apache.httpd The system may need to be restarted for the update to take effect.
Check Content
To check if the "Web Sharing" service is disabled, use the following command: /usr/bin/sudo /bin/launchctl print-disabled system | /usr/bin/grep org.apache.httpd If the results do not show the following, this is a finding. "org.apache.httpd" => true
Internet Sharing must be disabled.
Discussion
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Internet Sharing must be disabled.
Fix Text
This setting is enforced using the "Custom Policy" configuration profile.
Check Content
To check if the "Internet Sharing" service is disabled, use the following command: /usr/sbin/system_profiler SPConfigurationProfileDataType | /usr/bin/grep -A 2 'forceInternetSharingOff' If there is no result, or if "forceInternetSharingOff" is not set to "1", this is a finding.
The system must not send IPv4 ICMP redirects by default.
Discussion
ICMP redirects are broadcast in order to reshape network traffic. A malicious user could use the system to send fake redirect packets and try to force all network traffic to pass through a network sniffer. Disabling ICMP redirect broadcasts mitigates this risk.
Fix Text
To configure the system to not send "ICMP redirects", add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.ip.redirect=0
Check Content
To check if the system is configured to send "ICMP redirects", run the following command: sysctl net.inet.ip.redirect If the values are not set to "0", this is a finding.
The system must not send IPv6 ICMP redirects by default.
Discussion
ICMP redirects are broadcast in order to reshape network traffic. A malicious user could use the system to send fake redirect packets and try to force all network traffic to pass through a network sniffer. Disabling ICMP redirect broadcasts mitigates this risk.
Fix Text
To configure the system to not send "ICMP redirects", add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet6.ip6.redirect=0
Check Content
To check if the system is configured to send "ICMP redirects", run the following command: sysctl net.inet6.ip6.redirect If the values are not set to "0", this is a finding.
The system must prevent local applications from generating source-routed packets.
Discussion
A source-routed packet attempts to specify the network path that the system should take. If the system is not configured to block the sending of source-routed packets, an attacker can redirect the system's network traffic.
Fix Text
To configure the system to not forward "source-routed" packets, add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.ip.sourceroute=0
Check Content
To check if the system is configured to forward "source-routed" packets, run the following command: sysctl net.inet.ip.sourceroute If the value is not set to "0", this is a finding.
The operating system must employ automated mechanisms to detect the presence of unauthorized software on organizational information systems and notify designated organizational officials in accordance with the organization-defined frequency.
Discussion
An approved anti-virus product must be installed and configured to run. Malicious software can establish a base on individual desktops and servers. Employing an automated mechanism to detect this type of software will aid in elimination of the software from the operating system.
Fix Text
Install an approved anti-virus solution onto the system.
Check Content
Ask the SA or ISSO if an approved anti-virus solution is loaded on the system. The anti-virus solution may be bundled with an approved host-based security solution. If there is no local anti-virus solution installed on the system, this is a finding.
The system must not process Internet Control Message Protocol [ICMP] timestamp requests.
Discussion
ICMP Timestamp requests reveal information about the system and can be used to determine which operating system is installed. Precise time data can also be used to launch time based attacks against the system. Configuring the system to drop incoming ICMPv4 timestamp requests mitigates these risks.
Fix Text
To disable "ICMP timestamp" responses, add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.icmp.timestamp=0
Check Content
To check if the system is configured to process "ICMP timestamp" requests, run the following command: sysctl net.inet.icmp.timestamp If the value is not set to "0", this is a finding.
Unused network devices must be disabled.
Discussion
If an unused network device is left enabled, a user might be able to activate it at a later time. Unused network devices should be disabled.
Fix Text
To disable a network device, run the following command, substituting the name of the device in place of "'<networkservice>'": /usr/bin/sudo /usr/sbin/networksetup -setnetworkserviceenabled '<networkservice>' off
Check Content
To list the network devices that are enabled on the system, run the following command: /usr/bin/sudo /usr/sbin/networksetup -listallnetworkservices A disabled device will have an asterisk in front of its name. If any listed device that is not in use is missing this asterisk, this is a finding.
The operating system must generate audit records when successful/unsuccessful attempts to access/modify/delete objects, access/modify categories of information (e.g., classification levels), and delete privileges occur.
Discussion
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Satisfies: SRG-OS-000458-GPOS-00203, SRG-OS-000461-GPOS-00205, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209, SRG-OS-000466-GPOS-00210, SRG-OS-000467-GPOS-00211, SRG-OS-000468-GPOS-00212, SRG-OS-000474-GPOS-00219
Fix Text
To make sure the appropriate flags are enabled for auditing, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak '/^flags/ s/$/,fm/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the "/etc/security/audit_control" file.
Check Content
In order to view the currently configured flags for the audit daemon, run the following command: /usr/bin/sudo /usr/bin/grep ^flags /etc/security/audit_control If "fm" is not listed in the result of the check, this is a finding.