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Detection rules › Sigma

Microsoft Word Add-In Loaded

Status
test
Severity
low
Log source
product windows, category image_load
Author
Steffen Rogge (dr0pd34d)
Source
github.com/SigmaHQ/sigma

Detects Microsoft Word loading an Add-In (.wll) file which can be used by threat actors for initial access or persistence.

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1204.002 User Execution: Malicious File

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: Microsoft Word Add-In Loaded
id: 1337afba-d17d-4d23-bd55-29b927603b30
status: test
description: |
    Detects Microsoft Word loading an Add-In (.wll) file which can be used by threat actors for initial access or persistence.
references:
    - https://labs.withsecure.com/publications/add-in-opportunities-for-office-persistence
    - https://nored0x.github.io/red-teaming/office-persistence/#what-is-a-wll-file
author: Steffen Rogge (dr0pd34d)
date: 2024-07-10
tags:
    - attack.execution
    - attack.t1204.002
    - detection.threat-hunting
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith: '\winword.exe'
        ImageLoaded|endswith: '.wll'
    condition: selection
falsepositives:
    - The rules is only looking for ".wll" loads. So some false positives are expected with legitimate and allowed WLLs.
level: low

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Image|endswith: '\winword.exe'
    ImageLoaded|endswith: '.wll'

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
  • \winword.exe corpus 20 (sigma 20)
ImageLoadedends_with
  • .wll