AU-2(4): Privileged Functions

AU-2(4) requires you to explicitly identify which “privileged functions” in your environment must be audited, then ensure audit logging is actually enabled and reviewable for those actions across systems and tools where administrators operate. Operationalize it by maintaining a privileged-function audit matrix, implementing log collection/alerting, and retaining evidence that logging and review are working. ¹

Key takeaways:

• Define “privileged functions” for your environment and map them to log sources, events, and owners. ¹
• Turn on and centrally collect audit logs for privileged actions across identity, endpoints, servers, cloud, and security tooling. ²
• Keep recurring evidence: configurations, sample events, coverage reports, and review/response records tied to privileged activity. ²

The au-2(4): privileged functions requirement lives in the Audit and Accountability family for a reason: if you cannot reliably see what privileged users and privileged processes did, you cannot investigate incidents, prove change control, or demonstrate separation of duties. AU-2 is about “audit events” you decide to log; AU-2(4) narrows that focus to the highest-risk subset: privileged functions.

For a Compliance Officer, CCO, or GRC lead, the fastest path to readiness is to treat AU-2(4) as a scoping-and-coverage control. Your job is to force clarity on three questions: (1) what actions count as privileged in your environment, (2) where those actions occur (systems, services, tools), and (3) what evidence proves you are logging and reviewing them consistently. The most common audit failure is not “no logs exist.” It’s “logging exists in some places, but you can’t show complete coverage for privileged operations, or you can’t demonstrate the logs are reviewed and acted on.”

This page gives requirement-level implementation guidance you can hand to control owners and then test like an auditor.

Regulatory text

Provided excerpt: “NIST SP 800-53 control AU-2.4.” ¹

Operator interpretation of what you must do: AU-2(4) is the enhancement titled Privileged Functions. In practice, you must (a) identify the privileged functions relevant to your system and mission, and (b) ensure those privileged actions are included in the audit event set you log, retain, and can review. Treat “privileged functions” as actions performed with elevated permissions that can change security posture, access, configuration, or audit trails. ²

Plain-English interpretation (what AU-2(4) is really asking)

AU-2(4) expects you to audit what administrators and privileged services do, not just what normal users do. That means you can answer, with evidence, questions like:

• Who granted admin access, changed IAM policies, or edited firewall rules?
• Who disabled logging, altered audit settings, or deleted logs?
• Who changed authentication settings, MFA requirements, or key management settings?

A clean way to phrase the control objective: Privileged activity must be observable, attributable, and reviewable. ²

Who it applies to

Entity types (typical applicability):

• Federal information systems
• Contractor systems handling federal data ¹

Operational context (where this shows up in real programs):

• Systems in scope for NIST SP 800-53 Rev. 5 baselines (often via RMF, agency ATO processes, or contractual flow-downs). ²
• Environments with privileged roles: system administrators, cloud administrators, database administrators, security engineers, and automation identities (service accounts, CI/CD runners) that can perform admin-grade actions.

What you actually need to do (step-by-step)

Use this as an implementation runbook. Assign a single control owner (often Security Operations or IAM), with GRC accountable for evidence quality.

Step 1: Define “privileged functions” for your environment

Create a short, explicit definition you can enforce. Include both human and non-human privilege.

• Human: admin console access, root/sudo actions, domain admin actions, security tool admin actions.
• Non-human: service principals that can modify IAM, networks, endpoints, or logging configurations.

Output artifact: “Privileged Functions Definition” section in your logging standard. ²

Step 2: Build a Privileged Function Audit Matrix (PFAM)

This is the core operational deliverable for AU-2(4). Build a table with these columns:

Privileged function category	Concrete examples	Systems where it occurs	Log source	Event IDs / event types	Collection method	Retention location	Review owner

Populate it across your stack:

• Identity/IAM (role grants, policy changes, MFA changes)
• OS/admin actions (sudo, group changes, remote management)
• Directory services (admin group changes)
• Cloud control plane (security group, IAM policy, KMS changes)
• Network/security devices (firewall rule edits, WAF policy changes)
• Security tooling (EDR exclusions, SIEM config changes, alert suppression)
• Logging pipeline itself (changes to log forwarding, retention, deletion)

Pass/fail test: you can point to each privileged function and show exactly where its audit trail lives. ¹

Step 3: Confirm logging is enabled and tamper-resistant enough for your risk

For each PFAM row:

• Verify audit logging is turned on in the source system.
• Verify logs include an actor (user/service), action, target object, timestamp, and result.
• Verify logs are forwarded to a centralized platform (SIEM/log platform) where privileged users cannot silently erase evidence.

This step often requires coordination with platform teams. Your role is to push for consistency and document exceptions with compensating monitoring. ²

Step 4: Centralize collection and normalize privileged activity events

AU-2(4) becomes auditable when you can query privileged actions across the environment.

• Define a small set of normalized “privileged activity” event categories (e.g., “Privilege Granted,” “Audit Disabled,” “Policy Changed”).
• Map raw events into those categories for reporting and review.

Practical tip: auditors respond well to a repeatable query pack (saved searches) tied to PFAM rows. ²

Step 5: Implement review, alerting, and escalation for high-risk privileged actions

AU-2(4) is an event selection requirement, but auditors will still test whether the logs are usable for oversight. Put minimum operational muscle behind it:

• Alert on “rare, high-impact” privileged actions (disabling logging, changing auth settings, creating new admin principals, changing network boundaries).
• Route alerts to a monitored queue (SOC, on-call, ticketing).
• Require evidence of triage and closure notes.

Keep this pragmatic. Focus on the privileged actions that would break investigations or enable persistence. ²

Step 6: Run a coverage check and fix gaps

Do a structured gap review:

• PFAM rows with no log source identified
• Logs enabled but not forwarded
• Logs forwarded but missing key fields (no actor, no target)
• Central retention exists but queries/dashboards are not defined
• Privileged actions performed through third-party tools (RMM, MSP portals) without equivalent logging

Track remediations as backlog items with owners and expected completion. ²

Step 7: Operationalize evidence production (recurring)

Treat AU-2(4) evidence like a monthly control:

• Export a coverage report (PFAM + confirmation checks).
• Capture sample privileged events from each major log source.
• Record review outcomes for privileged-activity alerts or reports.

If you use Daydream to run your control library, map AU-2(4) to a named control owner, a written procedure, and a defined evidence set so you can produce the same package every audit without rebuilding it. ¹

Required evidence and artifacts to retain

Auditors will ask for proof of both design and operation. Retain these artifacts in a controlled repository:

1. Privileged Function Audit Matrix (PFAM) with systems, event types, and owners. ¹
2. Logging configuration evidence for key sources (screenshots/exports of audit settings enabled). ²
3. Log forwarding/collection evidence (agent configs, cloud export settings, SIEM ingestion status). ²
4. Sample log records showing privileged actions (actor, action, target, timestamp, outcome). ²
5. Saved searches/dashboards or query pack tied to privileged activity categories. ²
6. Review and response records (tickets/IR notes) for privileged-activity alerts or periodic reviews. ²
7. Exception register for any privileged areas not fully logged, with compensating controls and timeline. ²

Common exam/audit questions and hangups

Expect these lines of questioning:

• “Define privileged functions for this system.” If your definition is vague, you will fail scoping. Bring your written definition and PFAM. ²
• “Show me evidence that privileged actions are logged in system X.” Have config exports and sample events ready. ²
• “Can privileged users disable logging without detection?” This is a classic hangup. Document controls around audit configuration changes and alerting. ²
• “How do you cover cloud console and API activity?” Your PFAM must include control-plane logging sources, not only OS logs. ²
• “What about third parties and managed services?” If an MSP performs privileged actions, you still need auditability. Capture logs from their portal/tooling or require equivalent reporting. ²

Frequent implementation mistakes (and how to avoid them)

1. Mistake: Treating “admin login” as sufficient.
   Fix: audit the action (policy changed, role granted), not just the session. ²

2. Mistake: Logging exists, but no coverage map.
   Fix: maintain the PFAM and update it when new systems/tools are introduced. ¹

3. Mistake: Logging pipeline changes are not treated as privileged.
   Fix: include “audit disabled/modified” as privileged functions and alert on them. ²

4. Mistake: No owner for review.
   Fix: assign review ownership per PFAM row (SOC, IAM, Cloud Sec) and require a review record. ²

5. Mistake: Ignoring non-human privilege.
   Fix: include service accounts, automation, CI/CD, and API keys that can perform admin actions. ²

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so this page does not cite specific actions or settlements.

Operational risk is still straightforward: if privileged actions are not logged and reviewable, you will struggle to detect misconfiguration, insider abuse, account takeover, and unauthorized changes. You also increase the chance that incident response cannot establish a reliable timeline or scope. ²

Practical 30/60/90-day execution plan

Use phased execution without making promises about completion speed. Your environment size drives effort.

First 30 days (establish scope and minimum viable evidence)

• Appoint AU-2(4) control owner and reviewers by domain (IAM, cloud, endpoints, network). ²
• Draft the privileged functions definition and approve it with Security and IT leadership. ²
• Build PFAM for the highest-impact platforms (identity provider, primary cloud, SIEM/log platform, endpoint management). ¹
• Collect baseline evidence: screenshots/exports of audit settings and sample privileged events. ²

Days 31–60 (close coverage gaps and make review real)

• Extend PFAM to remaining in-scope systems, including security tools and networking. ²
• Turn on missing audit categories and forward logs centrally where feasible. ²
• Create saved searches/dashboards for privileged function categories and document review steps. ²
• Stand up alerting for a short list of highest-risk privileged actions (audit disabled, new admin, auth policy changes). ²

Days 61–90 (make it durable and audit-ready)

• Run an internal “audit drill”: pick privileged actions and trace them from source to SIEM to review record. ²
• Formalize exception handling and compensating monitoring where full logging is not possible. ²
• Schedule recurring evidence collection and review cadence; store artifacts consistently. ²
• In Daydream, tie AU-2(4) to the PFAM, a procedure, and recurring evidence tasks so control operation is trackable and repeatable. ¹

Frequently Asked Questions

What counts as a “privileged function” under AU-2(4)?

Treat it as any action performed with elevated permissions that can change access, security configuration, system behavior, or auditability. Write your definition and then map it to specific actions and log sources in a privileged function audit matrix. ²

Do we have to log every admin action everywhere?

AU-2(4) pushes you to include privileged functions in your audited event set, so you need defensible coverage for the systems in scope. Use a risk-based PFAM to show you identified privileged actions and enabled logging where they occur, with documented exceptions. ²

How do we handle privileged actions performed by a third party (MSP, cloud consultant)?

Require auditability in the operational model: either you ingest logs from the third party’s admin tooling/portal, or the third party provides activity records that you can review and retain. Record the approach in the PFAM and your third-party requirements. ²

What evidence do auditors usually want first for AU-2(4)?

Start with the PFAM, then show configurations that enable privileged auditing and sample events that prove the logs contain actor/action/target and are centrally available. Finally, show review records (tickets or reports) tied to privileged activity. ²

Our admins can change logging settings. Is that automatically a control failure?

Not automatically, but it is a predictable audit hangup. Treat changes to audit configurations as privileged functions, log them, and implement monitoring so disabling or reducing audit coverage is detectable and reviewable. ²

How does AU-2(4) relate to our SIEM and detection engineering work?

AU-2(4) is the requirement driver that makes privileged-activity logs non-negotiable; the SIEM is usually the system that proves you can collect and review those logs centrally. Build saved searches and alerting tied to the PFAM so you can show repeatable oversight. ²

Footnotes

1. NIST SP 800-53 Rev. 5 OSCAL JSON

2. NIST SP 800-53 Rev. 5