Detection rules › Sigma

Invoke-Obfuscation VAR+ Launcher - Security

Severity
high
Author
Jonathan Cheong, oscd.community
Source
upstream

Detects Obfuscated use of Environment Variables to execute PowerShell

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.001 Command and Scripting Interpreter: PowerShell
Defense EvasionT1027 Obfuscated Files or Information

Event coverage

ProviderEvent IDTitle
Security-Auditing4697A service was installed in the system.

Stages and Predicates

Stage 1: selection

or:
ServiceFileName|contains: '/c'
ServiceFileName|contains: '/r'
ServiceFileName|contains: -f
ServiceFileName|contains: '"set'
ServiceFileName|contains: cmd

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
ServiceFileNamematch
  • "set
  • -f corpus 2 (sigma 2)
  • /c corpus 3 (sigma 3)
  • /r
  • cmd corpus 5 (sigma 5)

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.