Detection rules › Sigma

CLR DLL Loaded Via Office Applications

Status
test
Severity
medium
Log source
category image_load, product windows
Author
Antonlovesdnb
Source
github.com/SigmaHQ/sigma

Detects CLR DLL being loaded by an Office Product

MITRE ATT&CK coverage

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 7: Image loaded

Rule body

title: CLR DLL Loaded Via Office Applications
id: d13c43f0-f66b-4279-8b2c-5912077c1780
status: test
description: Detects CLR DLL being loaded by an Office Product
references:
    - https://medium.com/threatpunter/detecting-adversary-tradecraft-with-image-load-event-logging-and-eql-8de93338c16
author: Antonlovesdnb
date: 2020-02-19
modified: 2023-03-29
tags:
    - attack.execution
    - attack.t1204.002
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: '\clr.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: '\clr.dll'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Imageends_with
  • \excel.exe corpus 16 (sigma 16)
  • \mspub.exe corpus 10 (sigma 10)
  • \onenote.exe corpus 6 (sigma 6)
  • \onenoteim.exe corpus 6 (sigma 6)
  • \outlook.exe corpus 13 (sigma 13)
  • \powerpnt.exe corpus 14 (sigma 14)
  • \winword.exe corpus 17 (sigma 17)
field:"Image" kind:ends_with
ImageLoadedmatch
  • \clr.dll
field:"ImageLoaded" kind:match value:"\clr.dll"