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Detection rules › Sigma

Suspicious PowerShell Invocation From Script Engines

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

Detects suspicious powershell invocations from interpreters or unusual programs

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.001 Command and Scripting Interpreter: PowerShell

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

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

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
CurrentDirectorymatch\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.

FieldKindValues
Imageends_with
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
ParentImageends_with
  • \cscript.exe corpus 17 (sigma 17)
  • \wscript.exe corpus 19 (sigma 19)