t1218-004-installutil

name	T1218.004_installutil
description	Adversaries may use InstallUtil to proxy execution of code through a trusted Windows utility.
category	configuration
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1218.004","defense-evasion","windows","sub-technique"]
technique_id	T1218.004
tactic	defense-evasion
all_tactics	["defense-evasion"]
platforms	["Windows"]
mitre_url	https://attack.mitre.org/techniques/T1218/004
tech_stack	["windows"]
cwe_ids	["CWE-693"]
chains_with	["T1218","T1218.001","T1218.002","T1218.003","T1218.005","T1218.007","T1218.008","T1218.009","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"}

T1218.004 InstallUtil

Sub-technique of: T1218

High-Level Description

Adversaries may use InstallUtil to proxy execution of code through a trusted Windows utility. InstallUtil is a command-line utility that allows for installation and uninstallation of resources by executing specific installer components specified in .NET binaries. The InstallUtil binary may also be digitally signed by Microsoft and located in the .NET directories on a Windows system: C:\Windows\Microsoft.NET\Framework\v\InstallUtil.exe and C:\Windows\Microsoft.NET\Framework64\v\InstallUtil.exe.

InstallUtil may also be used to bypass application control through use of attributes within the binary that execute the class decorated with the attribute [System.ComponentModel.RunInstaller(true)].

Kill Chain Phase

• Defense Evasion (TA0005)

Platforms: Windows

What to Check

• Identify if InstallUtil technique is applicable to target environment
• Check Windows systems for indicators of InstallUtil
• 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: CheckIfInstallable method call

Executes the CheckIfInstallable class constructor runner instead of executing InstallUtil. Upon execution, the InstallUtil test harness will be executed. If no output is displayed the test executed successfuly.

Supported Platforms: windows

# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

$InstallerAssemblyDir = "#{assembly_dir}"
$InstallerAssemblyFileName = "#{assembly_filename}"
$InstallerAssemblyFullPath = Join-Path -Path $InstallerAssemblyDir -ChildPath $InstallerAssemblyFileName

$ExpectedOutput = 'Constructor_'

$TestArgs = @{
    OutputAssemblyDirectory = $InstallerAssemblyDir
    OutputAssemblyFileName = $InstallerAssemblyFileName
    InvocationMethod = '#{invocation_method}'
}

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs -MinimumViableAssembly

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
CheckIfInstallable method execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}