DLL Loaded From Suspicious Location Via Cmspt.EXE — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-08-30 / 2023-02-17.

{
  "category": "image_load",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 1076ecced55d632cec91ec405f61824b780f269191ced738d0f333ae97930a5c

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: DLL Loaded From Suspicious Location Via Cmspt.EXE
id: 75e508f7-932d-4ebc-af77-269237a84ce1
status: test
description: Detects cmstp loading "dll" or "ocx" files from suspicious locations
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
author: Nasreddine Bencherchali (Nextron Systems)
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:
            # Add more suspicious paths as you see fit in your env
            - '\PerfLogs\'
            - '\ProgramData\'
            - '\Users\'
            - '\Windows\Temp\'
            - 'C:\Temp\'
        ImageLoaded|endswith:
            - '.dll'
            - '.ocx'
    condition: selection
falsepositives:
    - Unikely
level: high

Original YAML and metadata in JSON

False positives

• Unikely

Source 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