sigmamediumHunting

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.

Detection Query

selection_parent:
  ParentImage|endswith: \explorer.exe
selection_img:
  - Image|endswith: \rundll32.exe
  - OriginalFileName: RUNDLL32.EXE
filter_main_generic:
  - CommandLine|contains: " C:\\Windows\\System32\\"
  - CommandLine|endswith: " -localserver 22d8c27b-47a1-48d1-ad08-7da7abd79617"
condition: all of selection_* and not 1 of filter_main_*

Author

CD_ROM_

Created

2022-05-21

Data Sources

windowsProcess Creation Events

Platforms

windows

References

Tags

attack.defense-evasion

Raw Content

title: Rundll32 Spawned Via Explorer.EXE
id: 1723e720-616d-4ddc-ab02-f7e3685a4713
status: test
description: 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.
references:
    - https://redcanary.com/blog/raspberry-robin/
    - https://thedfirreport.com/2022/09/26/bumblebee-round-two/
author: CD_ROM_
date: 2022-05-21
modified: 2023-08-31
tags:
    - attack.defense-evasion
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith: '\explorer.exe'
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    filter_main_generic:
        - CommandLine|contains: ' C:\Windows\System32\' # The space at the start is required
        - CommandLine|endswith: ' -localserver 22d8c27b-47a1-48d1-ad08-7da7abd79617' # Windows 10 volume control
    condition: all of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium