Rundll32 Spawned Via Explorer.EXE

Detects execution of "rundll32.exe" with a parent process of Explorer.exe. This has been observed by variants of Raspberry Robin, as first reported by Red Canary.

Sigma rule (View on GitHub)

 1title: Rundll32 Spawned Via Explorer.EXE
 2id: 1723e720-616d-4ddc-ab02-f7e3685a4713
 3status: test
 4description: Detects execution of "rundll32.exe" with a parent process of Explorer.exe. This has been observed by variants of Raspberry Robin, as first reported by Red Canary.
 5references:
 6    - https://redcanary.com/blog/raspberry-robin/
 7    - https://thedfirreport.com/2022/09/26/bumblebee-round-two/
 8author: CD_ROM_
 9date: 2022/05/21
10modified: 2023/08/31
11tags:
12    - attack.defense_evasion
13logsource:
14    category: process_creation
15    product: windows
16detection:
17    selection_parent:
18        ParentImage|endswith: '\explorer.exe'
19    selection_img:
20        - Image|endswith: '\rundll32.exe'
21        - OriginalFileName: 'RUNDLL32.EXE'
22    filter_main_generic:
23        - CommandLine|contains: ' C:\Windows\System32\' # The space at the start is required
24        - CommandLine|endswith: ' -localserver 22d8c27b-47a1-48d1-ad08-7da7abd79617' # Windows 10 volume control
25    condition: all of selection_* and not 1 of filter_main_*
26falsepositives:
27    - Unknown
28level: medium

References

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