Suspicious BitLocker Access Agent Update Utility Execution

Hunt Hypothesis

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 i

Detection Rule

Sigma (Original)

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

KQL (Azure Sentinel)

imProcessCreate
| where (ParentProcessName endswith "\\baaupdate.exe" or ActingProcessName endswith "\\baaupdate.exe") and (TargetProcessName endswith "\\bitsadmin.exe" or TargetProcessName endswith "\\cmd.exe" or TargetProcessName endswith "\\cscript.exe" or TargetProcessName endswith "\\mshta.exe" or TargetProcessName endswith "\\powershell_ise.exe" or TargetProcessName endswith "\\powershell.exe" or TargetProcessName endswith "\\regsvr32.exe" or TargetProcessName endswith "\\rundll32.exe" or TargetProcessName endswith "\\schtasks.exe" or TargetProcessName endswith "\\wmic.exe" or TargetProcessName endswith "\\wscript.exe")

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Lateral Movement
• Technique: T1218 — T1218
• Technique: T1021.003 — T1021.003

References

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