A signed executable is a program file accompanied by a digital signature. The signature can help identify the publisher and detect changes made to the file after signing. Operating systems and security tools may use this information when assessing whether a program is trusted.
A valid signature does not guarantee that a program is safe or that every component it loads is trustworthy. For example, a legitimate signed application may load a malicious DLL if its search behavior lets an attacker influence where the library is found. Defenders should verify signatures, keep software updated, and monitor unexpected files, launch locations, and loaded components rather than relying on a publisher name alone.