Monitor Communications for Attacks

Monitor organizational systems, including inbound and outbound communications traffic, to detect attacks and indicators of potential attacks.

Think of indicators of attack as a set of footprints an adversary leaves during an attack. Indicators of attack provide information on the steps the adversary followed and its intent. Indicators of attacks on organizational systems may include: • internal traffic that indicates the presence of malicious code; • anomalous activity detected during non-business hours; • unauthorized data leaving the organization; and • communicating to external information systems. To detect attacks and indicators of attacks, deploy monitoring devices or agents. Place these sensors at strategic points within the systems and networks to collect essential information. Strategic points include internal and external system boundaries. Monitor both inbound traffic and outbound traffic as well as actions on hosts. This requirement, SI.L2-3.14.6, provides details for the communications of organizational systems. SI.L2-3.14.6 supports the requirement AU.L2-3.3.1, which involves creating and retaining records for monitoring, analysis, and investigations. Example It is your job to look for known indicators of attack or anomalous activity within your systems and communications traffic [a,b,c]. Because these indicators can show up in a variety of places on your network, you have created a checklist of places to check each week. These include the office firewall logs, the audit logs of the file server where CUI is stored, and the connection log for your VPN gateway [b]. You conduct additional reviews when you find an indicator, or something that does not perform as it should [a]. Potential Assessment Considerations • Are details provided for the methodology of determining attacks and indicators of attack [a]? • Are monitoring devices deployed within the information system to collect information that may indicate an attack [a]? • Are communications traffic flows understood and is there a deployed capability to review that traffic [b,c]?