Signature
Unique identifier of a malicious file
A signature is a small piece of data which uniquely identifies an individual item of malware, allowing anti-malware software to spot it when scanning files.
Most anti-malware products include a database of such signatures representing all malware known to the program. These databases are updated regularly with the identification strings for new items added by the product's developers. Whenever a product scans a new file, it is checked against the database to determine if it matches any known item.
Signatures can be made more flexible to allow for generic detection of similar items of malware. Too much flexibility can lead the signature to match other files, leading to false positives.
