Requirement text: AU.3.051: Correlate audit record review, analysis, and reporting processes for
investigation and response to indications of unlawful, unauthorized, suspicious, or
unusual activity.
DISCUSSION FROM SOURCE: DRAFT NIST SP 800-171 R2
Correlating audit record review, analysis, and reporting processes helps to ensure that they
do not operate independently, but rather collectively. Regarding the assessment of a given
organizational system, the requirement is agnostic as to whether this correlation is applied
at the system level or at the organization level across all systems.
CMMC CLARIFICATION
Organizations must review, analyze, and report audit records to help detect and respond to
security incidents in a timely manner for the purpose of investigation and corrective actions.
Collection of audit logs into one or more central repositories (per AM.3.048) facilitates
correlated review. Small organizations may be able to accomplish this manually. Larger
organizations will use an automated system for analysis that does correlation of log
information across the entire enterprise and supports the use of centralized intel feeds. By
centralizing intel feeds, subscription costs should be reduced and the effectiveness of the
analysis should be increased. Some organizations may want to orchestrate the entire
analysis process which includes the use of APIs for collection, correlation, and the
automation of responses based on programed rulesets.
Example 1
You are in charge of IT operations in your organization. You are responsible for assisting in
the investigation of a possible incident. You review the event log for suspicious activity, e.g.,
a user logged on at an unusual time of day. In order to analyze the data, you use an automated
tool to collect and analyze the audit log data, and perform queries to generate a detailed
report. Once the connection is made between the individual and the incident, corrective
actions are taken.
Example 2
You are a member of an adversary hunt team responsible for audit log analysis. You run an
automated tool that analyzes all the audit logs across a LAN segment simultaneously looking
for similar anomalies on separate systems at separate locations. After extracting anomalous
information and performing a correlation analysis, you determine that four different
systems have had their event log information cleared between 2:00 AM to 3:00 AM, although
the associated dates are different. The hunt team monitors all systems on the same LAN
segment between 2:00 AM to 3:00 AM for the next 30 days.
References
• NIST SP 800-171 Rev 1 3.3.5
• CIS Controls v7.1 6.6, 6.7
• NIST CSF v1.1 DE.AE-3
• CERT RMM v1.2 COMP: SG3.SP1
• NIST SP 800-53 Rev 4 AU-6(3)