Network devices must authenticate all IGP peers.
Interior routing protocols are not authenticated.
A rogue router could send a fictitious routing update to convince a site's premise router to send traffic to an incorrect or even a rogue destination. This diverted traffic could be analyzed to learn confidential information of the site's network, or merely used to disrupt the network's ability to effectively communicate with other networks.
Configure authentication for all IGP peers.
Review the device configuration to determine if authentication is configured for all IGP peers. If authentication is not configured for all IGP peers, this is a finding.
Information Assurance Officer