Detection rules › Sigma

PowerShell Core DLL Loaded Via Office Application

Status
test
Severity
medium
Log source
product windows, category image_load
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects PowerShell core DLL being loaded by an Office Product

MITRE ATT&CK coverage

TacticTechniques
StealthNo specific technique

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: PowerShell Core DLL Loaded Via Office Application
id: bb2ba6fb-95d4-4a25-89fc-30bb736c021a
status: test
description: Detects PowerShell core DLL being loaded by an Office Product
references:
    - Internal Research
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-01
tags:
    - attack.stealth
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith:
            - '\excel.exe'
            - '\mspub.exe'
            - '\outlook.exe'
            - '\onenote.exe'
            - '\onenoteim.exe' # Just in case
            - '\powerpnt.exe'
            - '\winword.exe'
        ImageLoaded|contains:
            - '\System.Management.Automation.Dll'
            - '\System.Management.Automation.ni.Dll'
    condition: selection
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Image|endswith:
        - '\excel.exe'
        - '\mspub.exe'
        - '\outlook.exe'
        - '\onenote.exe'
        - '\onenoteim.exe'
        - '\powerpnt.exe'
        - '\winword.exe'
    ImageLoaded|contains:
        - '\System.Management.Automation.Dll'
        - '\System.Management.Automation.ni.Dll'

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
  • \excel.exe corpus 18 (sigma 18)
  • \mspub.exe corpus 10 (sigma 10)
  • \onenote.exe corpus 6 (sigma 6)
  • \onenoteim.exe corpus 6 (sigma 6)
  • \outlook.exe corpus 14 (sigma 14)
  • \powerpnt.exe corpus 15 (sigma 15)
  • \winword.exe corpus 20 (sigma 20)
ImageLoadedmatch
  • \System.Management.Automation.Dll
  • \System.Management.Automation.ni.Dll