How to Make Database Audit Logs Truly Tamper-Proof, Not Just Trusted by Convention

Most audit logs rely on application-level promises to avoid edits or deletions, but bugs, rogue scripts, or compromised credentials can silently corrupt that history. A more reliable approach enforces immutability at the database layer itself, starting with granting the app role only INSERT and SELECT permissions on the audit table. Additional defenses include database triggers that reject any UPDATE or DELETE operations and hash-chained rows linked by foreign keys to make deletion structurally difficult. Each method has known bypass vectors — superusers can override permissions and disable triggers — so layering multiple techniques together provides stronger protection. For compliance scenarios requiring data erasure, appending a redaction event rather than deleting rows keeps the log tamper-evident while still satisfying legal obligations like GDPR.