Windows: cmstp.exe Loading DLL/OCX from Suspicious Paths

Alerts when cmstp.exe loads DLL/OCX from suspicious directories on Windows.

FreeReviewedSigma · High · v2

Product: windows
Category: image_load
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-08-30
Updated: 2026-07-31

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218.003CMSTP
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies executions where cmstp.exe loads a DLL or OCX from paths commonly abused for stealth, such as PerfLogs, ProgramData, Users, and temporary directories. Attackers can leverage the signed cmstp.exe binary as a proxy to load attacker-controlled libraries from unusual locations. The detection relies on image load telemetry that records the loaded module path (ImageLoaded) and the loading process (Image).

Reporting behind it

Related detections9 linkedT1218.003 — drag to rearrange

CMSTP Execution of an INF Profile (via process_creation)

Suspicious CMSTP Execution With INF Payload via process_creation

CMSTP UAC Bypass via Automatic Install Flag (via process_creation)

Windows Network Connection from Cmstp.EXE (Outbound)

Windows: Command-line execution of cmstp.exe with INF install/silent/autobind flags (UAC bypass pattern)

Windows CMSTP UAC Bypass Attempt via Autoelevate COM Object DllHost Execution

Windows Process Access to cmlua.dll by CMSTP Connection Manager Profile Installer

Windows CMSTP Process Spawning Child Process

Windows Registry Events: CMSTP Execution via cmmgr32.exe TargetObject

Windows: cmstp.exe Loading DLL/OCX from Suspicious Paths

Pivot detection · T1218.003 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-cmstp-loads-dll-ocx-from-suspicious-paths-75e508f7

title: "Windows: cmstp.exe Loading DLL/OCX from Suspicious Paths"
id: 5c244f40-58ad-4f2a-ab56-0031abbf088b
status: test
description: This rule identifies executions where cmstp.exe loads a DLL or OCX from paths commonly abused for stealth, such as PerfLogs, ProgramData, Users, and temporary directories. Attackers can leverage the signed cmstp.exe binary as a proxy to load attacker-controlled libraries from unusual locations. The detection relies on image load telemetry that records the loaded module path (ImageLoaded) and the loading process (Image).
references:
  - https://github.com/vadim-hunter/Detection-Ideas-Rules/blob/02bcbfc2bfb8b4da601bb30de0344ae453aa1afe/TTPs/Defense%20Evasion/T1218%20-%20Signed%20Binary%20Proxy%20Execution/T1218.003%20-%20CMSTP/Procedures.yaml
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_cmstp_load_dll_from_susp_location.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-08-30
modified: 2023-02-17
tags:
  - attack.stealth
  - attack.t1218.003
logsource:
  category: image_load
  product: windows
detection:
  selection:
    Image|endswith: \cmstp.exe
    ImageLoaded|contains:
      - \PerfLogs\
      - \ProgramData\
      - \Users\
      - \Windows\Temp\
      - C:\Temp\
    ImageLoaded|endswith:
      - .dll
      - .ocx
  condition: selection
falsepositives:
  - Unikely
level: high
license: DRL-1.1
related:
  - id: 75e508f7-932d-4ebc-af77-269237a84ce1
    type: derived

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