Audit

Enhanced Definition

In the mainframe context, an audit refers to the systematic and independent examination of system logs, security settings, application processes, and data to verify compliance with regulatory requirements, internal policies, and security standards. It ensures the integrity, confidentiality, and availability of critical business data and applications running on z/OS.

Key Characteristics

- Scope: Can range from specific application data access to overall system security configurations (RACF, ACF2, Top Secret) and operational procedures.
- Evidence-based: Relies heavily on system logs (SMF, SYSLOG), application-generated audit trails, JCL definitions, and security rule sets as primary sources of evidence.
- Regularity: Often performed periodically (e.g., quarterly, annually) or triggered by specific events (e.g., security incidents, system changes) to maintain continuous compliance.
- Independence: Ideally conducted by an independent party (internal audit department or external auditors) to ensure objectivity and unbiased findings.
- Compliance-driven: Primarily focused on meeting regulatory mandates (e.g., SOX, GDPR, HIPAA, PCI DSS) and internal governance policies.
- Automated Tools: Often leverages specialized mainframe audit tools and utilities to extract, analyze, and report on vast amounts of SMF and other log data.

Use Cases

- Regulatory Compliance: Verifying that financial transaction processing systems (CICS, DB2, IMS) comply with Sarbanes-Oxley (SOX) or other industry-specific regulations by reviewing access logs and change records.
- Security Policy Enforcement: Auditing RACF or ACF2 definitions and SMF records to ensure that only authorized users have access to sensitive data sets, programs, and system commands, and that security violations are detected.
- Change Management Verification: Reviewing SMF type 92 records (for z/OS UNIX file system activity) or ISPF audit trails to confirm that system and application changes were implemented according to approved procedures and without unauthorized modifications.
- Data Integrity Checks: Examining application logs and database audit trails (DB2 Audit Facility, IMS Log) to detect unauthorized data modifications, unusual access patterns, or potential data breaches.
- User Activity Monitoring: Analyzing SMF type 80 records for RACF events to track user logon/logoff, resource access attempts (both successful and failed), and privileged command usage.

Related Concepts

Auditing is intrinsically linked to mainframe security (RACF, ACF2, Top Secret), which defines the rules and controls that are then audited for effectiveness. It heavily relies on System Management Facilities (SMF), the primary source of system activity records, and SYSLOG for operational events and console messages. Application logging (e.g., CICS journals, DB2 logs, IMS logs) provides crucial evidence for application-level compliance. Effective auditing validates the effectiveness of these security and logging mechanisms and informs improvements to them.

Best Practices:

Define Clear Scope: Clearly articulate what is being audited, the systems involved, the specific compliance objectives, and the reporting requirements before starting any audit.
Automate Data Collection and Analysis: Utilize SMF exits, SYSLOG parsers, and specialized audit tools to automatically collect, filter, and correlate relevant data, minimizing manual effort and improving accuracy.
Regular Review of Security Rules: Periodically audit and review RACF profiles, ACF2 rules, and Top Secret access definitions to ensure they remain current, enforce desired policies, and remove stale access.
Secure Audit Trails: Protect SMF data sets, SYSLOG files, and application logs from unauthorized modification or deletion to maintain their integrity and non-repudiation as evidence.
Implement Alerting for Critical Events: Configure real-time monitoring and alerting for critical security events or policy violations detected in audit logs to enable prompt investigation and response.
Document Procedures and Findings: Maintain comprehensive documentation of audit procedures, findings, remediation actions, and follow-up activities for future reference, continuous improvement, and external review.