Finally, we have the context required to make an SIEM audit checklist meaningful. SIEM audits are vital processes that make sure your SIEM solution is working as intended, and its configuration still meets your organization's security needs. Many organizations run through a checklist like this annually or even several times a year.
Your SIEM audit checklist should be tailored to your industry, niche, and the way you do business. But a good place to start might look like the following:
1. Log source inventory
Take a look at the various logs that are feeding into your SIEM system, and make sure they’re all relevant. More importantly, make sure none are missing.
2. Retention and integrity verification
Make sure your SIEM system is retaining all of the logs you need for forensic analysis and compliance purposes. Also, make sure it’s retaining them in an intact, useful manner.
3. Rule coverage
The rules your SIEM uses must be aligned with your actual security needs. They must also be specific, narrowly defined, and contextual. Expect to redefine them often.
4. Alert review and false-positive rates
This can be crucial. Too high a false positive rate, and you need to reassess your rules. But if the false positive rate is too low, you might be missing too many real threats.
5. Response time metrics
The choice of KPIs is crucial as well. We suggest starting with MTTD (Mean Time To Detect). The shorter your MTTD, the better.
6. Access and privilege controls
Audit who has access to your SIEM system and review their permissions. Make sure the principle of least privilege is enforced, multi-factor authentication (MFA) is enabled, and role-based access controls are in place to limit potential misuse or accidental exposure.
7. Compliance mapping
Confirm that your SIEM alerts and reports map to relevant regulatory frameworks, like PCI, CMMC, HIPAA, or GDPR. Make sure that auditors can quickly and easily extract the required evidence to demonstrate compliance.
8. System health and maintenance
Audit patching, software updates, and performance baselines to maintain your SIEM system. Check storage use, indexing performance, and other operational metrics to prevent downtime or degraded SIEM performance.
9. Documentation and evidence storage
Just how long your SIEM retains logs and security event data is important to its forensic use as well as for compliance purposes. Ideally, this data should be divided into different classes, each with its own retention policies.