A loaded module is a library or software component that a running process has brought into memory. On Windows, this often means a dynamic-link library (DLL). Modules can provide functions the program needs, but they can also extend or change the process’s behavior.
This matters in security because a trusted, signed application may load an untrusted module if its library search paths are weak or attacker-controlled. In DLL side-loading, an attacker places a malicious DLL where a legitimate program will find it; the code then runs inside that program’s process. Defenders can reduce risk by keeping applications patched, restricting writable locations used for loading, and monitoring module-load events for unexpected files or paths. A valid signature on the main executable does not establish that every module it loads is safe.