AU-9: Protection of Audit Information

The au-9: protection of audit information requirement means you must protect audit logs and the logging systems themselves from unauthorized access, modification, and deletion. Operationalize AU-9 by locking down log access, hardening and segregating logging tooling, enforcing immutability or write-once protections where feasible, and producing clear evidence that these protections work in production ¹.

Key takeaways:

• Treat audit logs as sensitive records: control who can read them, and strictly limit who can change or delete them ¹.
• Protect the logging pipeline, not only the stored logs, because compromised tooling can erase or alter evidence ¹.
• Build assessor-ready proof: documented ownership, procedures, access reviews, and technical configurations tied to systems in scope ².

AU-9 is a control that fails quietly until you have an incident, an insider event, or an external compromise. If an attacker can tamper with audit logs, your detection, response, and legal defensibility degrade fast. Assessors also focus on AU-9 because it is easy to claim “we log everything,” while harder to prove “those logs cannot be altered or deleted by the wrong people.”

This requirement applies to federal information systems and contractor systems handling federal data, and it is commonly inherited or mapped into programs like FedRAMP and agency security requirements ². Practically, AU-9 becomes a set of decisions about role design, privileged access pathways, and technical controls that make log tampering difficult and detectable.

This page gives requirement-level implementation guidance you can execute: what AU-9 expects, which teams own each piece, how to implement protections across common logging architectures (SIEM, cloud-native logs, EDR), and what evidence you should retain so an auditor can validate operation without guesswork.

AU-9 requirement in plain English

AU-9 requires you to protect audit information and audit logging tools from three outcomes: unauthorized access, unauthorized modification, and unauthorized deletion ¹. Read that as:

1. keep the wrong people from reading logs,
2. keep almost everyone from changing logs, and
3. prevent “cleaning up” logs to hide activity.

It also covers the tools that create, ship, store, and query logs. If someone can change the logging configuration, disable log forwarding, or alter parsing rules, they can effectively “modify audit information” without touching the files.

Regulatory text

Excerpt: “Protect audit information and audit logging tools from unauthorized access, modification, and deletion; and” ¹

Operator translation: You must implement administrative and technical controls so that:

• Access to logs is restricted to approved roles with a business need.
• Modification and deletion of logs is prevented or tightly controlled, and any permitted actions are strongly governed and traceable.
• Logging infrastructure (agents, collectors, pipelines, SIEM, cloud logging accounts/projects, and storage) is protected from tampering, including privileged misuse ².

Who it applies to (entity + operational context)

Entities:

• Federal information systems
• Contractor systems handling federal data ²

Operationally, AU-9 applies anywhere you generate or handle security-relevant logs, including:

• Identity systems (IdP, SSO, MFA)
• Privileged access management and admin consoles
• Endpoint and server telemetry (EDR)
• Network and firewall logs
• Cloud control plane events
• Application and database audit trails
• Central log platforms (SIEM, log analytics, data lake)

If you outsource logging to a third party SIEM or managed detection provider, AU-9 still applies. The scope shifts to third-party controls and your ability to verify them contractually and operationally.

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

1) Assign ownership and define scope

• Name a control owner (often Security Engineering or SOC leadership) and a policy owner (often GRC/Compliance).
• Define systems in scope: where logs originate, how they move, and where they end up (collectors, brokers, SIEM, storage).
• Create a one-page AU-9 control narrative that maps: people, process, technology, and evidence. This aligns with NIST expectations for assessability ².

2) Classify audit logs and set handling rules

• Classify audit logs as sensitive operational/security data.
• Specify handling requirements: encryption, retention alignment (as defined elsewhere in your program), and restrictions on export/sharing.
• Decide which logs are “security audit logs” vs. “operational logs,” then apply AU-9 protections at least to security audit logs.

3) Lock down access (read vs. administer vs. delete)

Create separate roles with separate privileges:

• Log Readers/Analysts: can search and view logs, cannot change logging configuration, cannot delete or edit.
• Log Platform Admins: can manage pipelines and integrations, but cannot erase evidence without a controlled break-glass process.
• Storage/Infrastructure Admins: limited and monitored access to underlying storage; direct access should be the exception.

Implementation moves that auditors expect to see:

• Role-based access control (RBAC) on SIEM/log platform.
• Strong authentication and MFA on all logging systems.
• Restrictions on API keys/service accounts that can alter pipelines or retention settings.

4) Protect integrity and deletion pathways

AU-9 explicitly calls out modification and deletion ¹. Your design goal: make tampering difficult and visible.

• Centralize logs into a controlled platform rather than leaving them scattered on hosts.
• Write-once / immutable storage where feasible for critical security logs (for example, immutable object storage features or append-only indexes). If you cannot make storage immutable, implement compensating controls: restricted admin paths, strong monitoring, and independent backups.
• Separation of duties: the person who administers endpoints should not be the only person with power to delete endpoint logs in the SIEM.
• Break-glass deletion: if deletion is ever permitted (rare), require ticketing approval, time-bound access, and post-action review.

5) Protect the logging tools and pipeline

Attackers often target the pipeline first. Treat the following as high-risk assets:

• Log forwarders/agents, collectors, and syslog relays
• SIEM connectors/parsers
• Cloud logging projects/accounts and IAM policies
• Time synchronization sources, because skewed time reduces log evidentiary value

Controls to implement:

• Hardening baselines for logging servers/collectors.
• Network segmentation so only approved sources can send logs.
• Configuration change control for logging rules, filters, and retention settings.
• Monitoring/alerting for “logging stopped,” “agent disabled,” “collector unreachable,” and “log volume dropped” conditions.

6) Prove the control works (operational checks)

Build recurring checks your team can execute and retain:

• Access review of who can administer the SIEM and who can delete data.
• Configuration review of retention/immutability settings for key log repositories.
• Test case: attempt to delete or alter logs from a non-authorized role and record the outcome.
• Incident response drill artifact: demonstrate your team can retrieve logs quickly and show chain-of-custody controls.

7) Map AU-9 to evidence artifacts (make it audit-ready)

A common failure mode is “implemented, but not provable.” Track AU-9 as a requirement with named evidence outputs. A simple way to operationalize this is to map AU-9 to a control owner, a written procedure, and a recurring evidence pack ¹. Daydream is useful here because it helps you standardize control narratives and evidence requests across systems and third parties without rebuilding checklists for every audit.

Required evidence and artifacts to retain

Keep artifacts that show both design and operation:

• AU-9 control narrative: scope, systems, roles, and tooling.
• Access control evidence:
  • RBAC role matrix for logging tools
  • Screenshots/exports of admin role assignments
  • MFA enforcement configuration for SIEM/log platform
• Integrity/deletion protections:
  • Configuration evidence for immutability/append-only settings (if used)
  • Retention and deletion policy settings and change logs
  • Break-glass procedure and approval workflow (ticket examples with redactions)
• Change management:
  • Change tickets for logging pipeline modifications
  • Version control records for logging-as-code (if applicable)
• Monitoring and alerting:
  • Alerts for log pipeline failures
  • Incident records showing response to logging interruptions

Common exam/audit questions and hangups

Expect these lines of questioning:

• “Who can delete logs, and how do you prevent a privileged admin from covering tracks?”
• “Show me where you protect the logging tool itself, not only the logs.”
• “How do you detect a disabled agent or a drop in log volume?”
• “Prove separation of duties between system admins and log administrators.”
• “Show evidence this is reviewed and not just configured once.”

Hangups that cause findings:

• One “super-admin” group that can do everything across SIEM, cloud IAM, and storage.
• No documented process for emergency access.
• Logs stored in locations where standard admins can purge them.

Frequent implementation mistakes (and how to avoid them)

1. Assuming “read-only dashboards” equals protected logs.
   Dashboards are a front end. Check backend permissions and storage deletion rights.

2. Leaving the logging account/project as a shared admin playground.
   Create a dedicated logging/security account boundary and restrict IAM.

3. Relying on a third party without verification.
   If a third party hosts your SIEM, validate contract terms, role design, and deletion controls. Ask for evidence you can retain.

4. No evidence discipline.
   AU-9 failures often show up as “could be compliant, but cannot demonstrate.” Set recurring evidence collection and retention as part of the control.

Enforcement context and risk implications

No public enforcement cases were provided in the supplied source catalog for AU-9. Operationally, assessors and incident responders treat log tampering risk as high-impact because it affects containment, forensics, and reporting credibility. If you cannot demonstrate log integrity protections, expect broader scrutiny across incident response, monitoring, and privileged access controls ².

Practical 30/60/90-day execution plan

Use a phased plan without assuming fixed calendar outcomes for your environment.

First 30 days (stabilize + define)

• Confirm in-scope systems and logging architecture diagram.
• Assign AU-9 control owner and approvers.
• Document roles and current permissions for SIEM/log platforms and storage.
• Identify top tampering risks: direct delete permissions, shared admin accounts, unmonitored pipeline failures.

By 60 days (implement protections + governance)

• Implement RBAC separation for reader vs. admin vs. delete-capable roles.
• Add break-glass workflow for any deletion/config changes.
• Harden logging tooling: MFA, network restrictions, change control.
• Implement monitoring for logging interruptions and material drops in log volume.

By 90 days (prove operation + evidence pack)

• Run an access review and retain output as evidence.
• Execute a tamper test (attempted deletion/modification) and document results.
• Package AU-9 evidence: control narrative, configs, access lists, review records.
• If logging is outsourced, collect third-party evidence and store it with your AU-9 control record.

Frequently Asked Questions

Do I need immutable storage to meet AU-9?

AU-9 requires protection from unauthorized modification and deletion ¹. Immutability is a strong control, but you can also meet the intent with strict RBAC, separation of duties, monitored admin actions, and controlled break-glass deletion with approvals.

Who should be allowed to delete audit logs?

Aim for “almost nobody.” If deletion is necessary for operational reasons, restrict it to a tightly controlled role with approvals, time-bound access, and reviewable audit trails, and document the process as part of your AU-9 procedure ².

Does AU-9 apply to application logs or only security logs?

It applies to audit information and logging tools in scope for your system ¹. Many teams prioritize security-relevant audit trails first (identity, admin actions, access, security events) and then expand protections to high-risk application logs that support investigations.

What evidence does an assessor usually expect for AU-9?

Evidence that access is restricted, admin actions are governed, and logs cannot be modified or deleted by unauthorized roles ¹. Provide role assignments, configuration exports, screenshots, access review records, and change/break-glass tickets.

How do we handle AU-9 if a third party runs our SIEM?

Put contractual and operational controls in place so the third party cannot alter or delete logs without your authorization, and so you can obtain evidence on request. Keep their control attestations, access model, and operational reports in your AU-9 evidence pack.

What’s the fastest way to get AU-9 audit-ready?

Start by mapping AU-9 to a named owner, a written procedure, and a recurring evidence set tied to specific systems and roles ¹. Tools like Daydream help standardize that mapping and keep the evidence collection consistent across audits.

Footnotes

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

2. NIST SP 800-53 Rev. 5