An unsigned installer is a software package that does not carry a valid digital signature from a trusted publisher. Digital signatures help confirm that the file has not been altered and that it came from the expected source. Without that check, users and security tools have less assurance about integrity and origin.
In cyber attacks, unsigned installers are often used to make malicious software easier to distribute and harder to verify, especially when it imitates a legitimate app or extension. They may appear in phishing downloads, fake update prompts, or repackaged tools. Defenders treat unsigned installers as a warning sign: they should be checked against known-good hashes, blocked by application-control policies, and verified before execution. For users, a missing signature is not proof of malware, but it is a strong reason to pause and confirm the source.