Sysmon, short for System Monitor, is a Windows telemetry tool from Microsoft that records detailed security-relevant activity on an endpoint. It can log process creation, network connections, file changes, registry activity, and image loads, which makes it far more useful for threat hunting than basic event logs alone.
In cyber security, Sysmon is especially valuable for spotting DLL side-loading and other module-abuse techniques. Defenders can use its image-load events to see which process loaded which DLL, whether the library came from an unusual or user-writable path, and whether a signed executable is running code from an unexpected module. That visibility helps detect malware hiding inside trusted Windows tools and supports allowlisting, incident response, and behavior-based detections. In real environments, the key question is often not just what ran, but what it loaded and from where.