Suspicious PowerShell Invocation From Script Engines

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects suspicious powershell invocations from interpreters or unusual programs

Known false positives

Microsoft Operations Manager (MOM)
Other scripts

MITRE ATT&CK coverage

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

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Suspicious PowerShell Invocation From Script Engines
id: 95eadcb2-92e4-4ed1-9031-92547773a6db
status: test
description: Detects suspicious powershell invocations from interpreters or unusual programs
references:
    - https://www.securitynewspaper.com/2017/03/20/attackers-leverage-excel-powershell-dns-latest-non-malware-attack/
author: Florian Roth (Nextron Systems)
date: 2019-01-16
modified: 2023-01-05
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\wscript.exe'
            - '\cscript.exe'
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
    filter_health_service:
        CurrentDirectory|contains: '\Health Service State\'
    condition: selection and not 1 of filter_*
falsepositives:
    - Microsoft Operations Manager (MOM)
    - Other scripts
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_*

Stage 1: `selection`

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

Stage 2: `not filter_health_service`

filter_health_service:
    CurrentDirectory|contains: '\Health Service State\'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`CurrentDirectory`	match	`\Health Service State\`	`excludes:CurrentDirectory` `field:"CurrentDirectory" value:"\Health Service State\"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Image`	ends_with	`\powershell.exe` corpus 179 (sigma 178, kusto 1) `\pwsh.exe` corpus 165 (sigma 164, kusto 1)	`field:"Image" kind:ends_with`
`ParentImage`	ends_with	`\cscript.exe` corpus 17 (sigma 17) `\wscript.exe` corpus 19 (sigma 19)	`field:"ParentImage" kind:ends_with`

Suspicious PowerShell Invocation From Script Engines

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_health_service

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_health_service`