Suspicious CustomShellHost Execution — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-08-19 / 2025-10-29.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: ecf3532694b5bc13d3be81aa1a925108d2d89a1a6e9566a647fa2693c2dd65e8

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: Suspicious CustomShellHost Execution
id: 84b14121-9d14-416e-800b-f3b829c5a14d
status: test
description: |
    Detects the execution of CustomShellHost.exe where the child isn't located in 'C:\Windows\explorer.exe'. CustomShellHost is a known LOLBin that can be abused by attackers for defense evasion techniques.
references:
    - https://github.com/LOLBAS-Project/LOLBAS/pull/180
    - https://lolbas-project.github.io/lolbas/Binaries/CustomShellHost/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-19
modified: 2025-10-29
tags:
    - attack.stealth
    - attack.t1216
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\CustomShellHost.exe'
    filter_main_explorer:
        Image: 'C:\Windows\explorer.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - False positives are unlikely, investigate matches carefully.
level: high

Original YAML and metadata in JSON

False positives

• False positives are unlikely, investigate matches carefully.

Source references

• https://github.com/LOLBAS-Project/LOLBAS/pull/180
• https://lolbas-project.github.io/lolbas/Binaries/CustomShellHost/