File integrity monitoring (FIM) is an internal control or process that performs the act of validating the integrity of operating system and application software files using a verification method between the current file state and a known, good baseline.
This comparison method often involves calculating a known cryptographic checksum of the file’s original baseline and comparing with the calculated checksum of the current state of the file. Other file attributes can also be used to monitor integrity.
Generally, the act of performing file integrity monitoring is automated using internal controls such as an application or process. Such monitoring can be performed randomly, at a defined polling interval, or in real-time.