How an audit trail works
Systems, applications, databases, and network devices generate log entries for security-relevant events. Each entry should include a timestamp, the user or service identity, the action, the target resource, and the result. Collected together, these entries form a timeline that can be reconstructed later.
For the trail to be trustworthy, it must be protected. Logs are usually sent to a central platform such as a SIEM, where they are stored with integrity controls and restricted access, so that an attacker or insider cannot quietly edit or delete them. Accurate clocks across systems are essential.
Why it matters for Canadian organizations
After an incident, regulators, insurers, and customers want to know what was accessed and when. PIPEDA and Law 25 require organizations to assess whether a breach creates a real risk of significant harm, and that assessment is difficult without reliable records of data access.
Audit trails are also routine audit evidence for ISO 27001, SOC 2, PCI DSS, and OSFI B-13 expectations around monitoring and incident handling. Missing logs can turn a contained event into an unresolved one, since investigators cannot confirm what an intruder did.
How to implement it
Decide which events matter most: authentication, privilege changes, access to sensitive data, administrative actions, and security tool changes. Enable logging for them across endpoints, servers, cloud services, and applications, and forward everything to a central, protected store.
Set retention periods that match legal and contractual needs, and test that logs can actually be searched. Alerting on suspicious patterns turns a passive record into an active control, and periodic reviews confirm that coverage has not drifted as systems change. Test retrieval periodically so evidence is available when an investigation starts.
Frequently asked questions
What is the difference between an audit trail and a log?
A log is a raw record produced by a system. An audit trail is a curated, protected collection of those records organized to show a sequence of activity for accountability. In practice, audit trails are built from logs. Without that curation and protection, raw logs are harder to trust or present as evidence.
How long should audit trails be kept?
It depends on legal, regulatory, and contractual requirements, so there is no single answer. Many organizations retain security logs for a year or more, with recent data kept searchable. Check your sector rules and insurer expectations.
Can audit trails be altered by attackers?
They can if they are stored only on the compromised system. That is why logs should be forwarded quickly to a separate, access-controlled platform with integrity protections, so tampering is difficult and detectable. Restricting who can modify them is equally important.
Related service: SIEM and log monitoring