Suspicious BitLocker Access Agent Update Utility Execution — Sigma Rule

Rule metadata and linked tags

Author: andrewdanis, Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2025-10-18 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0b2b65e9f5691d701d7ccd9a0499d02a9a1791ed112e61038caab55b7f4e9da7

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious BitLocker Access Agent Update Utility Execution
id: 9f38c1db-e2ae-40bf-81d0-5b68f73fb512
related:
    - id: 6e8fe0a8-ba0b-4a93-8f9e-82657e7a5984 # BaaUpdate.exe Suspicious DLL Load
      type: similar
status: experimental
description: |
    Detects the execution of the BitLocker Access Agent Update Utility (baaupdate.exe) which is not a common parent process for other processes.
    Suspicious child processes spawned by baaupdate.exe could indicate an attempt at lateral movement via BitLocker DCOM & COM Hijacking.
references:
    - https://github.com/rtecCyberSec/BitlockMove
author: andrewdanis, Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-10-18
tags:
    - attack.stealth
    - attack.t1218
    - attack.lateral-movement
    - attack.t1021.003
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\baaupdate.exe'
        Image|endswith:
            - '\bitsadmin.exe'
            - '\cmd.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\powershell_ise.exe'
            - '\powershell.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\schtasks.exe'
            - '\wmic.exe'
            - '\wscript.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/rtecCyberSec/BitlockMove