Potential COM Object Hijacking Via TreatAs Subkey - Registry

Hunt Hypothesis

Detects COM object hijacking via TreatAs subkey

Detection Rule

Sigma (Original)

title: Potential COM Object Hijacking Via TreatAs Subkey - Registry
id: 9b0f8a61-91b2-464f-aceb-0527e0a45020
status: test
description: Detects COM object hijacking via TreatAs subkey
references:
    - https://bohops.com/2018/08/18/abusing-the-com-registry-structure-part-2-loading-techniques-for-evasion-and-persistence/
author: Kutepov Anton, oscd.community
date: 2019-10-23
modified: 2025-10-26
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1546.015
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains|all:
            - 'HKU\'
            - 'Classes\CLSID\'
            - '\TreatAs'
    filter_main_svchost:
        # Example of target object by svchost
        # TargetObject: HKU\S-1-5-21-1098798288-3663759343-897484398-1001_Classes\CLSID\{0003000A-0000-0000-C000-000000000046}\TreatAs
        Image: 'C:\WINDOWS\system32\svchost.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Maybe some system utilities in rare cases use linking keys for backward compatibility
level: medium
regression_tests_path: regression_data/rules/windows/registry/registry_set/registry_set_persistence_com_key_linking/info.yml
simulation:
    - type: atomic-red-team
      name: COM hijacking via TreatAs
      technique: T1546.015
      atomic_guid: 33eacead-f117-4863-8eb0-5c6304fbfaa9

KQL (Azure Sentinel)

imRegistry
| where (RegistryKey endswith "HKU*" and RegistryKey endswith "Classes\\CLSID*" and RegistryKey contains "\\TreatAs") and (not(ActingProcessName =~ "C:\\WINDOWS\\system32\\svchost.exe"))

Required Data Sources

False Positive Guidance

• Maybe some system utilities in rare cases use linking keys for backward compatibility

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Tactic: Persistence
• Technique: T1546.015 — T1546.015

References

• https://bohops.com/2018/08/18/abusing-the-com-registry-structure-part-2-loading-techniques-for-evasion-and-persistence/
• SigmaHQ Rule