Analyze Communications Traffic Anomalies
LOW MODERATE HIGHRequirements NIST SOURCE
Analyze outbound communications traffic at the external interfaces to the system and selected [interior points] to discover anomalies.
Discussion (NIST Supplemental 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.
Implementation Guidance
Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.
No engineering interpretation has been authored for SI-4(11) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.
Assessment
Assessment Objectives
- interior points within the system where communications traffic is to be analyzed are defined;
- outbound communications traffic at the external interfaces to the system is analyzed to discover anomalies;
- outbound communications traffic at <SI-04(11)_ODP interior points> is analyzed to discover anomalies.
Examine
[SELECT FROM: System and information integrity policy; system and information integrity procedures; procedures addressing system monitoring tools and techniques; system design documentation; network diagram; system monitoring tools and techniques documentation; system configuration settings and associated documentation; system monitoring logs or records; system audit records; system security plan; other relevant documents or records].
Interview
[SELECT FROM: System/network administrators; organizational personnel with information security responsibilities; organizational personnel installing, configuring, and/or maintaining the system; organizational personnel responsible for monitoring the system; organizational personnel responsible for the intrusion detection system].
Test
[SELECT FROM: Organizational processes for intrusion detection and system monitoring; mechanisms supporting and/or implementing intrusion detection and system monitoring capabilities; mechanisms supporting and/or implementing the analysis of communications traffic].
Overlays
STIGs & CCIs
No STIG checks or CCI mappings are currently loaded for SI-4(11). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.
Learn more about STIG/CCI integration →Evidence
Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.
Policy
- System and information integrity policy
- system security plan
Configuration
- system design documentation
- system configuration settings and associated documentation
Testing
- Organizational processes for intrusion detection and system monitoring
- mechanisms supporting and/or implementing intrusion detection and system monitoring capabilities
- mechanisms supporting and/or implementing the analysis of communications traffic
Other Records
- system and information integrity procedures
- procedures addressing system monitoring tools and techniques
- network diagram
- system monitoring tools and techniques documentation
- system monitoring logs or records
- system audit records
- other relevant documents or records