system integrity check

A periodic or on-demand security verification process that examines a computing system's files, configurations, software, and runtime state against a known-good trusted baseline to confirm that no unauthorized or undetected alterations have occurred. It detects unauthorized changes — such as those caused by malware, intrusions, or misconfiguration — by comparing current values against known-good reference values, usually cryptographic hashes. Mechanically, this typically involves hashing executables, scripts, libraries, and other critical artifacts and checking them against a stored baseline, so that replacement by a malicious file causes an immediate failure. In practice, it supports incident detection and forensic investigation and demonstrates compliance with frameworks such as PCI DSS, which explicitly requires file integrity monitoring on critical systems.