Control statement
Allocate audit log storage capacity to accommodate [Organization-defined: audit log retention requirements].
Discussion
Organizations consider the types of audit logging to be performed and the audit log processing requirements when allocating audit log storage capacity. Allocating sufficient audit log storage capacity reduces the likelihood of such capacity being exceeded and resulting in the potential loss or reduction of audit logging capability.
Organization-defined parameters
These values must be resolved through the organization’s tailoring and governance process. Bracketed parameter references in the control text identify where a decision is required.
From control text to operational evidence
Use Audit Log Storage Capacity as a testable risk decision. Translate the official statement into accountable people, repeatable processes, configured technology, and evidence that demonstrates the outcome over time. In this family, pay particular attention to audit event design, trustworthy collection, retention, review, and investigation support.
Implementation workflow
- Define the control boundary, responsible owner, inherited portions, and systems or processes in scope.
- Resolve each organization-defined parameter before declaring the control implemented.
- Document how the implementation satisfies every clause of the official control statement.
- Collect evidence as a normal byproduct of operation rather than only before an assessment.
- Review exceptions, changes, and monitoring results on a risk-based cadence.
Evidence examples
- logging standards and event-selection decisions
- sample audit records and retention settings
- time-synchronization evidence
- alert and review records
Common failure patterns
- collecting logs without defined use cases
- critical events missing from the audit trail
- retention shorter than investigative needs
- logs accessible to the same administrators being monitored
Questions practitioners should ask
- What risk decision is this control intended to support in this system?
- Which parts are implemented locally, inherited, shared, or not applicable—and what evidence supports that decision?
- Do the documented narrative, deployed configuration, operating process, and collected evidence agree?
- What event or threshold requires the implementation to be reviewed or changed?
Assessment objectives and methods
Show the assessment objective
audit log storage capacity is allocated to accommodate [Organization-defined: audit log retention requirements].
Examine
- Audit and accountability policy
- procedures addressing audit storage capacity
- system security plan
- privacy plan
- system design documentation
- system configuration settings and associated documentation
- audit record storage requirements
- audit record storage capability for system components
- system audit records
- other relevant documents or records
Interview
- Organizational personnel with audit and accountability responsibilities
- organizational personnel with information security and privacy responsibilities
- system/network administrators
- system developers
Test
- Audit record storage capacity and related configuration settings
Related controls
These relationships come from the official OSCAL catalog. They indicate useful dependencies or context, not automatic inheritance or equivalence.
Related defensive techniques
D3FEND maps this base control or one of its enhancements to the following defensive techniques. The ontology relation label is preserved and does not by itself prove implementation or effectiveness.
MITRE D3FEND™ and the D3FEND logo are trademarks of The MITRE Corporation. Bare Metal Cyber is not affiliated with or endorsed by MITRE.
Control enhancements
Enhancements add specificity, strength, or scope to the base control. Baseline badges show explicit selections in the official SP 800-53B OSCAL profiles.
AU-4(1) — Transfer to Alternate Storage
Transfer audit logs [Organization-defined: frequency] to a different system, system component, or media other than the system or system component conducting the logging.
Official discussion
Audit log transfer, also known as off-loading, is a common process in systems with limited audit log storage capacity and thus supports availability of the audit logs. The initial audit log storage is only used in a transitory fashion until the system can communicate with the secondary or alternate system allocated to audit log storage, at which point the audit logs are transferred. Transferring audit logs to alternate storage is similar to [AU-9(2)](#au-9.2) in that audit logs are transferred to a different entity. However, the purpose of selecting [AU-9(2)](#au-9.2) is to protect the confidentiality and integrity of audit records. Organizations can select either control enhancement to obtain the benefit of increased audit log storage capacity and preserving the confidentiality, integrity, and availability of audit records and logs.
Organization-defined parameters (1)
Assessment objectives and methods
audit logs are transferred [Organization-defined: frequency] to a different system, system component, or media other than the system or system component conducting the logging.
Examine
- Audit and accountability policy
- system security plan
- privacy plan
- procedures addressing audit storage capacity
- procedures addressing transfer of system audit records to secondary or alternate systems
- system design documentation
- system configuration settings and associated documentation
- logs of audit record transfers to secondary or alternate systems
- system audit records transferred to secondary or alternate systems
- other relevant documents or records
Interview
- Organizational personnel with audit storage capacity planning responsibilities
- organizational personnel with information security and privacy responsibilities
- system/network administrators
Test
- Mechanisms supporting the transfer of audit records onto a different system
Authoritative sources
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. Official control requirements and interpretations remain with NIST and the responsible authorizing organization.