Detection rules › Sigma

Suspicious CustomShellHost Execution

Severity
high
Author
Nasreddine Bencherchali (Nextron Systems)
Source
upstream

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

TacticTechniques
Defense EvasionT1216 System Script Proxy Execution

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation
Security-Auditing4688A new process has been created.

Stages and Predicates

Stage 1: selection

ParentImage|endswith: '\CustomShellHost.exe'

Stage 2: not 1 of filter_main_explorer

Image: '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.

FieldKindValues
Imageeq
  • C:\Windows\explorer.exe corpus 9 (sigma 9)
ParentImageends_with
  • \CustomShellHost.exe