GAC DLL Loaded Via Office Applications

 1title: GAC DLL Loaded Via Office Applications
 2id: 90217a70-13fc-48e4-b3db-0d836c5824ac
 3status: test
 4description: Detects any GAC DLL being loaded by an Office Product
 5references:
 6    - https://medium.com/threatpunter/detecting-adversary-tradecraft-with-image-load-event-logging-and-eql-8de93338c16
 7author: Antonlovesdnb
 8date: 2020/02/19
 9modified: 2023/02/10
10tags:
11    - attack.execution
12    - attack.t1204.002
13logsource:
14    category: image_load
15    product: windows
16detection:
17    selection:
18        Image|endswith:
19            - '\excel.exe'
20            - '\mspub.exe'
21            - '\onenote.exe'
22            - '\onenoteim.exe' # Just in case
23            - '\outlook.exe'
24            - '\powerpnt.exe'
25            - '\winword.exe'
26        ImageLoaded|startswith: 'C:\Windows\Microsoft.NET\assembly\GAC_MSIL'
27    condition: selection
28falsepositives:
29    - Legitimate macro usage. Add the appropriate filter according to your environment
30level: high