| name | SI-4(11)_analyze-communications-traffic-anomalies |
| description | Analyze outbound communications traffic at the external interfaces to the system and selected [organization-defined] to discover anomalies. |
| category | input-validation |
| version | 5.2.0 |
| author | cyberstrike-official |
| tags | ["nist","sp800-53","rev5","si-4-11","si","enhancement"] |
| tech_stack | ["aws","azure","gcp","linux","windows"] |
| cwe_ids | ["CWE-20"] |
| chains_with | [] |
| prerequisites | ["SI-4"] |
| severity_boost | {} |
SI-4(11) Analyze Communications Traffic Anomalies
Enhancement of: SI-4
High-Level Description
Family: System and Information Integrity (SI)
Framework: NIST SP 800-53 Rev 5
Organization-defined interior points include subnetworks and subsystems. Anomalies within organizational systems include large file transfers, long-time persistent connections, attempts to access information from unexpected locations, the use of unusual protocols and ports, the use of unmonitored network protocols (e.g., IPv6 usage during IPv4 transition), and attempted communications with suspected malicious external addresses.
What to Check
How to Test
Step 1: Review Documentation
Examine the System Security Plan (SSP) and related artifacts for SI-4(11) implementation details. Verify the organization has documented how this control is satisfied.
Step 2: Validate Implementation
# For cloud environments, use cloud-audit-mcp tools
# For on-premises, review system configurations directly
# Example: Check if account management policies exist
grep -r "account.management\|access.control" /etc/security/ 2>/dev/null
Step 3: Test Operating Effectiveness
Verify the control is actively functioning, not just documented. Check logs, configurations, and operational evidence.
Tools
| Tool | Purpose | Usage |
|---|
| cloud-audit-mcp | Check integrity monitoring | cloud_audit_monitoring |
| AWS CLI | Review GuardDuty/Inspector | aws guardduty list-detectors |
Remediation Guide
Control Statement
Analyze outbound communications traffic at the external interfaces to the system and selected [organization-defined] to discover anomalies.
Implementation Guidance
Organization-defined interior points include subnetworks and subsystems. Anomalies within organizational systems include large file transfers, long-time persistent connections, attempts to access information from unexpected locations, the use of unusual protocols and ports, the use of unmonitored network protocols (e.g., IPv6 usage during IPv4 transition), and attempted communications with suspected malicious external addresses.
