CMSTP
The Microsoft Connection Manager Profile Installer (CMSTP.exe) is a command-line program used to install Connection Manager service profiles. CMSTP.exe accepts an installation information file (INF) as a parameter and installs a service profile leveraged for remote access connections. Adversaries may supply CMSTP.exe with INF files infected with malicious commands.
Similar to Regsvr32 / ”Squiblydoo”, CMSTP.exe may be abused to load and execute DLLs and/or COM scriptlets (SCT) from remote servers. This execution may also bypass AppLocker and other whitelisting defenses since CMSTP.exe is a legitimate, signed Microsoft application. CMSTP.exe can also be abused to Bypass User Account Control and execute arbitrary commands from a malicious INF through an auto-elevated COM interface.
- Understand the behaviour - read the description and the Atomic Tests to see exactly what the attacker does on a host or network.
- Find the telemetry - what data source would reveal it (process creation, registry, network flow, auth logs). Detection Coverage shows which surfaces already have a rule and which are blind.
- Get or write the detection - adapt ready logic (CAR Analytics, SIEM Detections, Falco, or Sigma via Generate a SIEM detection), or author your own.
- Test it - run an Atomic Test in a lab and confirm your rule actually fires. A detection you have not tested is a hope, not coverage.
- Deploy and tune - push it, then watch for false positives and adjust.