t1218-009-regsvcsregasm

name	T1218.009_regsvcsregasm
description	Adversaries may abuse Regsvcs and Regasm to proxy execution of code through a trusted Windows utility.
category	configuration
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1218.009","defense-evasion","windows","sub-technique"]
technique_id	T1218.009
tactic	defense-evasion
all_tactics	["defense-evasion"]
platforms	["Windows"]
mitre_url	https://attack.mitre.org/techniques/T1218/009
tech_stack	["windows"]
cwe_ids	["CWE-693"]
chains_with	["T1218","T1218.001","T1218.002","T1218.003","T1218.004","T1218.005","T1218.007","T1218.008","T1218.010","T1218.011","T1218.012","T1218.013","T1218.014","T1218.015"]
prerequisites	["T1218"]
severity_boost	{"T1218":"Chain with T1218 for deeper attack path","T1218.001":"Chain with T1218.001 for deeper attack path","T1218.002":"Chain with T1218.002 for deeper attack path"}

T1218.009 Regsvcs/Regasm

Sub-technique of: T1218

High-Level Description

Adversaries may abuse Regsvcs and Regasm to proxy execution of code through a trusted Windows utility. Regsvcs and Regasm are Windows command-line utilities that are used to register .NET Component Object Model (COM) assemblies. Both are binaries that may be digitally signed by Microsoft.

Both utilities may be used to bypass application control through use of attributes within the binary to specify code that should be run before registration or unregistration: [ComRegisterFunction] or [ComUnregisterFunction] respectively. The code with the registration and unregistration attributes will be executed even if the process is run under insufficient privileges and fails to execute.

Kill Chain Phase

• Defense Evasion (TA0005)

Platforms: Windows

What to Check

• Identify if Regsvcs/Regasm technique is applicable to target environment
• Check Windows systems for indicators of Regsvcs/Regasm
• Verify mitigations are bypassed or absent (2 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Regasm Uninstall Method Call Test

Executes the Uninstall Method, No Admin Rights Required. Upon execution, "I shouldn't really execute either." will be displayed.

Supported Platforms: windows

C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe /r:System.EnterpriseServices.dll /out:"#{output_file}" /target:library "#{source_file}"
C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe /U #{output_file}

Dependencies:

• The CSharp source file must exist on disk at specified location (#{source_file})

Atomic Test 2: Regsvcs Uninstall Method Call Test

Executes the Uninstall Method, No Admin Rights Required, Requires SNK. Upon execution, "I shouldn't really execute" will be displayed along with other information about the assembly being installed.

Supported Platforms: windows Yes