Windows Registry COM InProcServer32 Hijack via PSFactory CLSID Default Value

ATT&CK techniques

Persistence → Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1546.015Component Object Model Hijacking
Priv Esc
- T1546.015Component Object Model Hijacking
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags changes to the PSFactory COM CLSID InProcServer32 (Default) registry value. COM in-proc server hijacking can provide persistence by redirecting a CLSID to load an attacker-controlled DLL instead of the expected binary. It relies on registry set telemetry for the specific CLSID path and filters out updates that point to the known ActXPrxy.dll locations.

Reporting behind it

Related detections9 linkedT1546.015 — drag to rearrange

Suspicious COM Hijack of ClickOnce Deployment Service CLSID (via registry_set)

Suspicious COM Hijack Via InprocServer32 Modification

Malicious COM Hijacking via TinyTurla CLSID InprocServer32 (via registry_set)

Suspicious dllhost.exe Spawned with CLSID and Anomalous Parent (via process_creation)

Suspicious COM Handler Hijack of MsCtfMonitor CLSID via CharmingCypress

Malicious COM Hijack of PSFactoryBuffer InprocServer32

Malicious APT-C-60 COM Hijack via SpyGlace CLSID InProcServer32 (via registry_set)

Malicious COM Hijack via CLSID InProcServer32 Registry Modification (via registry_set)

Malicious COM Object Hijack Pointing to a User-Writable DLL (via registry_set)

Windows Registry COM InProcServer32 Hijack via PSFactory CLSID Default Value

Pivot detection · T1546.015 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-registry-com-inprocserver32-hijack-via-psfactory-clsid-default-value-243380fa

title: Windows Registry COM InProcServer32 Hijack via PSFactory CLSID Default Value
id: 402617c4-67a2-413a-b8ef-badca4b5442d
status: test
description: This rule flags changes to the PSFactory COM CLSID InProcServer32 (Default) registry value. COM in-proc server hijacking can provide persistence by redirecting a CLSID to load an attacker-controlled DLL instead of the expected binary. It relies on registry set telemetry for the specific CLSID path and filters out updates that point to the known ActXPrxy.dll locations.
references:
  - https://blogs.blackberry.com/en/2023/06/romcom-resurfaces-targeting-ukraine
  - https://strontic.github.io/xcyclopedia/library/clsid_C90250F3-4D7D-4991-9B69-A5C5BC1C2AE6.html
  - https://www.virustotal.com/gui/file/6d3ab9e729bb03ae8ae3fcd824474c5052a165de6cb4c27334969a542c7b261d/detection
  - https://www.trendmicro.com/en_us/research/23/e/void-rabisu-s-use-of-romcom-backdoor-shows-a-growing-shift-in-th.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_persistence_comhijack_psfactorybuffer.yml
author: BlackBerry Threat Research and Intelligence Team - @Joseliyo_Jstnk, Huntrule Team
date: 2023-06-07
modified: 2023-08-17
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.t1546.015
logsource:
  category: registry_set
  product: windows
detection:
  selection:
    TargetObject|endswith: \CLSID\{c90250f3-4d7d-4991-9b69-a5c5bc1c2ae6}\InProcServer32\(Default)
  filter_main:
    Details:
      - "%windir%\\System32\\ActXPrxy.dll"
      - C:\Windows\System32\ActXPrxy.dll
  condition: selection and not filter_main
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 243380fa-11eb-4141-af92-e14925e77c1b
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL