What evidence do auditors commonly ask for on SI-4(18) System Monitoring | Analyze Traffic and Covert Exfiltration?

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.

What is the most common gap auditors find on SI-4(18)?

Outbound traffic is not analyzed at the defined interior points for covert exfiltration

NIST SP 800-53 Rev 5 · SI - System and Information Integrity

`SI-4(18)` System Monitoring | Analyze Traffic and Covert Exfiltration

Analyze outbound communications traffic at external interfaces to the system and at the following interior points to detect covert exfiltration of information: organization-defined interior points within the system.

Source: NIST SP 800-53 Rev 5, SI-4(18). The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open NIST SP 800-53 Rev 5 in the compliance library.

Base controls and their enhancements. Which apply follows the baseline you are assessed against (for example FedRAMP Moderate or High, or the low, moderate and high baselines of SP 800-53B). Text in square brackets is a parameter your organisation sets.

artefacts

held by a system

at each review

hard

to go live

Policy repository / GRC workspace

where the evidence lives

teal = a system already holds it · olive = produced at each review. To go live: easy when half or more of the artefacts are already held by a system, moderate from a quarter to a half, hard below a quarter.

These are the artefacts auditors commonly ask for on this requirement, our guidance rather than text from the standard. Your assessor decides what is sufficient in your context, and asks for samples across the period when a report covers one.

system holds itEvidence a system already holds

System monitoring logs or records · SIEM / log platform

periodic reviewEvidence produced at each review

System audit records · Policy repository / GRC workspace
Test of Organizational processes for intrusion detection and system monitoring; mechanisms supporting and/or implementing intrusion detection and system monitoring capabilities; mechanisms supporting and/or implementing an analysis of outbound communications traffic · SIEM / log platform

governing documentDocuments that govern the control

System and information integrity policy · Policy repository / GRC workspace
System and information integrity procedures · Policy repository / GRC workspace
Procedures addressing system monitoring tools and techniques · Policy repository / GRC workspace
System design documentation · Document repository
Network diagram · Policy repository / GRC workspace
System monitoring tools and techniques documentation · Policy repository / GRC workspace
System configuration settings and associated documentation · Policy repository / GRC workspace

First move

Mostly documents and reviews. Pull the 1 system-held artefact from your SIEM / log platform on a schedule; put the documents under version control with an owner and review date, and log each review as a dated record with a named reviewer.

Common gaps auditors find

Outbound traffic is not analyzed at the defined interior points for covert exfiltration
Covert exfiltration methods such as tunneling in allowed protocols are not examined

Do this for your whole sheet

Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.

Build my evidence sheet

SI-4(17) System Monitoring | Integrated Situational Awareness · SI-4(19) System Monitoring | Risk for Individuals