Detection rules › Sigma
Suspicious CustomShellHost Execution
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.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1216 System Script Proxy Execution |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
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
Stages and Predicates
Stage 0: condition
selection and not 1 of filter_main_*Stage 1: selection
selection:
ParentImage|endswith: '\CustomShellHost.exe'
Stage 2: not filter_main_explorer
filter_main_explorer:
Image: 'C:\Windows\explorer.exe'
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
Image | eq | C:\Windows\explorer.exe |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
ParentImage | ends_with |
|