Suspicious PowerShell Invocation From Script Engines

Severity: medium
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects suspicious powershell invocations from interpreters or unusual programs

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection`

or:
Image|endswith: '\powershell.exe'
Image|endswith: '\pwsh.exe'
or:
ParentImage|endswith: '\cscript.exe'
ParentImage|endswith: '\wscript.exe'

Stage 2: `not 1 of filter_health_service`

CurrentDirectory|contains: '\Health Service State\'

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
`CurrentDirectory`	match	`\Health Service State\`
`Image`	ends_with	`\powershell.exe` corpus 143 (sigma 143) `\pwsh.exe` corpus 140 (sigma 140)
`ParentImage`	ends_with	`\cscript.exe` corpus 14 (sigma 14) `\wscript.exe` corpus 14 (sigma 14)