Protection of Audit Information

To meet the protection of audit information requirement (NIST SP 800-53 Rev. 5 AU-9), you must secure audit logs and the logging systems themselves against unauthorized access, tampering, and deletion, and prove those protections work in daily operations. Implement strict access control, immutability or tamper-evidence, hardened logging infrastructure, and monitored retention workflows. ¹

Key takeaways:

• Treat logs and logging tools as high-value assets; lock down both the data and the pipeline. ¹
• Prevent modification/deletion through least privilege, separation of duties, and write-once/tamper-evident storage patterns. ¹
• Keep evidence that protections are enforced: access lists, configurations, alerting, and change records for logging components. ¹

“Protection of Audit Information” fails in predictable ways: too many admins can edit logs, the SIEM becomes a shared playground, agents can be disabled without detection, or log storage is purgeable by the same people who might be investigated. AU-9 closes those gaps by requiring that audit information and audit logging tools are protected from unauthorized access, modification, and deletion. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest path to operationalizing AU-9 is to define a small set of non-negotiables: who can access logs, who can administer logging, who can change retention, what makes logs tamper-evident, and how you detect interference with logging. Then you translate those decisions into enforceable technical controls across cloud control planes, operating systems, databases, applications, and your central logging platform.

This page is written for FedRAMP Moderate operators, but the implementation patterns apply broadly to regulated environments. The emphasis is evidence: you should be able to show an assessor not only that protections exist in design, but that they are continuously enforced through access control, configuration management, monitoring, and incident response workflows. ¹

Regulatory text

Requirement (AU-9): “Protect audit information and audit logging tools from unauthorized access, modification, and deletion.” ¹

Operator interpretation:
You must treat (1) audit logs and (2) the systems that generate, collect, process, and store those logs as protected assets. The requirement is not satisfied by “we send logs to a SIEM.” You need controls that (a) limit access, (b) prevent or strongly deter tampering, and (c) prevent deletion or make deletion controlled, detectable, and authorized. ¹

Plain-English meaning (what the assessor is looking for)

An assessor will probe three questions:

1. Can unauthorized people read sensitive logs? Logs can contain user identifiers, IPs, admin actions, object names, and sometimes payload fragments. AU-9 expects you to restrict access to only those with a job need. ¹
2. Can someone alter logs or hide actions? The classic failure is an admin who can edit or delete evidence. AU-9 expects technical and procedural barriers that prevent “covering tracks,” or at minimum make it detectable. ¹
3. Can someone disable logging tools or erase the pipeline? Protecting the logging toolchain matters as much as the stored log files. AU-9 requires protecting agents, forwarders, collectors, SIEM configurations, and retention settings. ¹

Who it applies to

Entity types: Cloud Service Providers and Federal Agencies operating systems within the FedRAMP Moderate boundary. ¹

Operational scope you should assume:

• Central logging platform (SIEM/log analytics) and its admin plane
• Log collectors/forwarders/agents
• Cloud-native audit sources (for example, control-plane events)
• OS and application audit logs
• Storage backing logs (object storage, managed service retention, archival tiers)
• Tooling that manages logging configuration (IaC pipelines, config management, EDR policies) ¹

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

Step 1: Define the protected set (logs + logging tools)

Create a short inventory that you can hand to an auditor:

• Audit information: what log types are in scope (cloud audit trails, OS logs, application audit logs, database audit logs, security tool logs)
• Audit logging tools: agents/collectors, SIEM, storage buckets/indices, alerting rules, log management APIs, and the CI/CD or IaC repos that control logging configuration ¹

Artifact: “Audit Logging Architecture & Asset Inventory” (diagram + table).

Step 2: Implement least privilege for log access

Make access decisions explicit and enforce them:

• Define roles: typical roles include “Log Reader,” “Security Analyst,” “SIEM Admin,” “Platform Admin (no SIEM admin),” and “Break-glass.”
• Restrict log read access: require SSO, MFA, and group-based access. Remove direct access to raw log storage for most users; prefer access through approved analytics views.
• Separate duties: the people who administer systems should not automatically have rights to edit/delete audit data or retention settings. ¹

Artifacts: access control policy for logging, RBAC mapping, group membership export, and approvals for privileged roles.

Step 3: Prevent modification and deletion (design for immutability or tamper-evidence)

Pick a pattern that your environment can support and document it. Common acceptable implementations include:

• Write-once / append-only storage controls for centralized log repositories.
• Object lock / immutability settings where supported by your storage layer.
• WORM-like retention controls for archives.
• Tamper-evident controls such as cryptographic integrity validation, or a design that makes edits non-viable (for example, no direct write permissions except ingest service accounts, and no delete permissions except tightly controlled lifecycle processes). ¹

Operational rule you should enforce: no human administrator has standing permission to delete or edit stored audit logs in the primary repository. If your platform requires some delete capability, confine it to a break-glass path with ticketing, approvals, and post-action review.

Artifacts: storage policy screenshots/exports, bucket/index permissions, retention configuration, and documented break-glass procedure.

Step 4: Harden and monitor the logging toolchain

AU-9 includes “audit logging tools,” so protect the components that make logging work:

• Lock down who can change SIEM parsing rules, ingestion endpoints, correlation rules, retention, and data routing.
• Protect log forwarders/agents from being disabled: restrict service stop/disable permissions, monitor for agent health drops, and alert on configuration drift.
• Treat logging configuration as controlled change: IaC/code review, change tickets, and peer approval for changes impacting audit collection and retention. ¹

Artifacts: change management records for logging config, SIEM admin access list, agent health dashboards, alerts for ingestion failures.

Step 5: Detect and respond to tampering attempts

You need evidence that interference becomes visible:

• Alert on changes to logging configuration, retention settings, and access policies.
• Alert on log ingestion gaps, collector downtime, and sudden drops in event volume for critical sources.
• Create an incident response playbook for “suspected log tampering / logging disabled,” including immediate preservation steps and escalation. ¹

Artifacts: alert rule list, recent alert samples, IR playbook excerpt, and incident tickets (sanitized).

Step 6: Prove it works with recurring checks

Make AU-9 survivable during staff turnover and platform evolution:

• Periodic access reviews for logging roles (readers and admins)
• Configuration reviews for retention and immutability settings
• Tests that break-glass works and is auditable
• Spot checks: attempt unauthorized delete/alter in a non-production environment and record the control behavior (blocked action, alert fired, ticket created). ¹

Artifacts: access review sign-offs, config baselines, test evidence, exception register.

Required evidence and artifacts to retain (audit-ready list)

Keep these in a single “AU-9 evidence packet” folder:

• Logging architecture diagram and inventory of audit sources and tools ¹
• RBAC matrix for log access vs. SIEM administration
• SSO/MFA enforcement proof for logging platforms (configuration export or screenshots)
• Permissions exports for log storage (who can read/write/delete)
• Retention and immutability configuration evidence (where supported)
• Change records for logging/retention/access policy changes
• Monitoring/alerting evidence for ingestion health and config changes
• Break-glass procedure + one completed break-glass exercise record
• Exceptions and compensating controls documentation ¹

Common exam/audit questions and hangups

• “Who can delete logs?” Expect scrutiny. If the answer is “all admins,” you will likely be pushed into remediation. ¹
• “Can a system administrator alter evidence about their own actions?” Separation of duties is the core practical hangup.
• “Show me how you detect logging being turned off.” Auditors want alerting and an incident workflow, not a statement.
• “Are audit logs protected in transit and at rest?” AU-9 focuses on access/modification/deletion, but in practice assessors will still expect you to show basic protection controls around the log pipeline. ¹
• “Where is the boundary?” FedRAMP assessments often hinge on whether you included cloud control-plane logs and managed service logs in the same protection model.

Frequent implementation mistakes (and how to avoid them)

1. Shared admin accounts in the SIEM. Fix with named accounts, SSO, and role-based permissions. ¹
2. Log storage is deletable by platform admins. Remove delete permissions; force lifecycle changes through controlled pipelines and approvals.
3. No monitoring for ingestion gaps. Add health alerts and make on-call ownership explicit.
4. Logging config changes are “out of band.” Bring them under change control like production code.
5. Treating “we have a SIEM” as the control. The control is protection from unauthorized access, modification, and deletion, plus evidence that those protections are enforced. ¹

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so you should assume assessors will evaluate AU-9 primarily through technical testing, configuration inspection, and evidence review. Operationally, weak AU-9 increases breach investigation risk: without trustworthy logs, you cannot reliably reconstruct events, validate containment, or demonstrate control effectiveness to an authorizing official. ¹

Practical 30/60/90-day execution plan

First 30 days: Stabilize and scope

• Name an AU-9 owner (usually Security Engineering or SecOps) and a GRC evidence owner.
• Build the inventory: audit sources, storage locations, SIEM, collectors, and configuration management points. ¹
• Pull current access lists for SIEM and log storage; identify who has delete/admin rights.
• Draft the RBAC model and separation-of-duties rule for logs and logging tools.

Next 60 days: Implement hard controls + evidence

• Enforce SSO/MFA for logging platforms; remove shared accounts.
• Remove standing delete and edit permissions from human roles in primary log stores; implement a controlled break-glass path.
• Lock down who can change retention, routing, and parsing rules; put changes behind tickets and approvals. ¹
• Add monitoring: ingestion gaps, agent health, configuration changes, and access policy changes.

By 90 days: Prove operational maturity

• Run an internal audit-style walkthrough: demonstrate denied delete attempts, show alerts, show change records.
• Complete an access review and document sign-off.
• Exercise the break-glass procedure and capture the evidence package.
• Centralize evidence collection. If you use Daydream, set AU-9 evidence requests to auto-collect access exports, config snapshots, and change tickets on a schedule so the control stays audit-ready. ¹

Frequently Asked Questions

Do we need “immutable storage” to satisfy AU-9?

AU-9 requires protection from unauthorized modification and deletion, not a specific technology choice. If you cannot make logs immutable, you need strong compensating controls that prevent deletion/modification by default and make any exception tightly controlled and detectable. ¹

Are SIEM detection rules and parsers considered “audit logging tools”?

Yes in practical scope, because changing them can alter what is captured, how it is interpreted, or whether it is retained. Restrict who can modify them and keep change records as evidence. ¹

Can platform administrators have access to logs?

They can if you document the need and enforce least privilege, but it is a common assessment risk if the same admins can also modify or delete logs. Separate “operate the platform” from “control the evidence.” ¹

What evidence is most persuasive to an assessor for AU-9?

Permission exports showing no standing delete rights, retention/immutability configuration proof, and real change tickets for logging configuration. Pair that with alert evidence for logging disruption. ¹

How do we handle third-party managed logging services in our boundary?

Treat the managed service configuration and access paths as “audit logging tools,” then control who can administer the service and who can change retention or export/delete settings. Keep contracts or service configurations in your evidence packet if they show those protections. ¹

What if engineers need to delete logs for debugging or cost control?

Don’t grant standing delete rights. Provide a controlled process for exclusions (for example, adjusting retention via approved change) and use break-glass only for exceptional, time-bound cases with after-the-fact review. ¹

Footnotes

1. NIST Special Publication 800-53 Revision 5