sigmaDRL-1.1from SigmaHQ/sigma

Potential AMSI COM Server Hijacking

Detects changes to the AMSI come server registry key in order disable AMSI scanning functionalities. When AMSI attempts to starts its COM component, it will query its registered CLSID and return a non-existent COM server. This causes a load failure and prevents any scanning methods from being accessed, ultimately rendering AMSI useless

Quality

100

FP risk

—

Forks

Views

ATT&CK techniques

T1562.001

Rule sourcerules/windows/registry/registry_set/registry_set_amsi_com_hijack.yml

title: Potential AMSI COM Server Hijacking
id: 160d2780-31f7-4922-8b3a-efce30e63e96
status: test
description: Detects changes to the AMSI come server registry key in order disable AMSI scanning functionalities. When AMSI attempts to starts its COM component, it will query its registered CLSID and return a non-existent COM server. This causes a load failure and prevents any scanning methods from being accessed, ultimately rendering AMSI useless
references:
    - https://enigma0x3.net/2017/07/19/bypassing-amsi-via-com-server-hijacking/
    - https://github.com/r00t-3xp10it/hacking-material-books/blob/43cb1e1932c16ff1f58b755bc9ab6b096046853f/obfuscation/simple_obfuscation.md#amsi-comreg-bypass
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-01-04
modified: 2023-08-17
tags:
    - attack.defense-evasion
    - attack.t1562.001
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|endswith: '\CLSID\{fdb00e52-a214-4aa1-8fba-4357bb0072ec}\InProcServer32\(Default)'
    filter:
        Details: '%windir%\system32\amsi.dll'
    condition: selection and not filter
falsepositives:
    - Unknown
level: high