ID	Name
T1546.001	Change Default File Association
T1546.002	Screensaver
T1546.003	Windows Management Instrumentation Event Subscription
T1546.004	.bash_profile and .bashrc
T1546.005	Trap
T1546.006	LC_LOAD_DYLIB Addition
T1546.007	Netsh Helper DLL
T1546.008	Accessibility Features
T1546.009	AppCert DLLs
T1546.010	AppInit DLLs
T1546.011	Application Shimming
T1546.012	Image File Execution Options Injection
T1546.013	PowerShell Profile
T1546.014	Emond
T1546.015	Component Object Model Hijacking

Adversaries may establish persistence by executing malicious content triggered by hijacked references to Component Object Model (COM) objects. COM is a system within Windows to enable interaction between software components through the operating system.^[1] References to various COM objects are stored in the Registry.

Adversaries can use the COM system to insert malicious code that can be executed in place of legitimate software through hijacking the COM references and relationships as a means for persistence. Hijacking a COM object requires a change in the Registry to replace a reference to a legitimate system component which may cause that component to not work when executed. When that system component is executed through normal system operation the adversary's code will be executed instead.^[2] An adversary is likely to hijack objects that are used frequently enough to maintain a consistent level of persistence, but are unlikely to break noticeable functionality within the system as to avoid system instability that could lead to detection.

ID: T1546.015

Sub-technique of: T1546

Tactics: Privilege Escalation, Persistence

Platforms: Windows

Permissions Required: User

Data Sources: DLL monitoring, Loaded DLLs, Process command-line parameters, Process monitoring, Windows Registry

Contributors: Elastic

Version: 1.0

Created: 16 March 2020

Last Modified: 09 July 2020

Version Permalink

Live Version

Procedure Examples

Name	Description
ADVSTORESHELL	Some variants of ADVSTORESHELL achieve persistence by registering the payload as a Shell Icon Overlay handler COM object.^[3]
APT28	APT28 has used COM hijacking for persistence by replacing the legitimate `MMDeviceEnumerator` object with a payload.^[4]^[10]
BBSRAT	BBSRAT has been seen persisting via COM hijacking through replacement of the COM object for MruPidlList `{{42aedc87-2188-41fd-b9a3-0c966feabec1}}` or Microsoft WBEM New Event Subsystem `{{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}}` depending on the system's CPU architecture.^[8]
ComRAT	ComRAT samples have been seen which hijack COM objects for persistence by replacing the path to shell32.dll in registry location `HKCU\Software\Classes\CLSID{{42aedc87-2188-41fd-b9a3-0c966feabec1}}\InprocServer32`.^[6]
JHUHUGIT	JHUHUGIT has used COM hijacking to establish persistence by hijacking a class named MMDeviceEnumerator and also by registering the payload as a Shell Icon Overlay handler COM object ({{3543619C-D563-43f7-95EA-4DA7E1CC396A}}).^[4]^[5]
KONNI	KONNI has modified ComSysApp service to load the malicious DLL payload.^[9]
Mosquito	Mosquito uses COM hijacking as a method of persistence.^[7]

Mitigations

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Detection

There are opportunities to detect COM hijacking by searching for Registry references that have been replaced and through Registry operations (ex: Reg) replacing known binary paths with unknown paths or otherwise malicious content. Even though some third-party applications define user COM objects, the presence of objects within HKEY_CURRENT_USER\Software\Classes\CLSID\ may be anomalous and should be investigated since user objects will be loaded prior to machine objects in HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID.^[11] Registry entries for existing COM objects may change infrequently. When an entry with a known good path and binary is replaced or changed to an unusual value to point to an unknown binary in a new location, then it may indicate suspicious behavior and should be investigated.

Likewise, if software DLL loads are collected and analyzed, any unusual DLL load that can be correlated with a COM object Registry modification may indicate COM hijacking has been performed.