Home/ATT&CK Technique/InstallUtil
ATT&CK Technique

InstallUtil

T1218.004 · stealth

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<version>\InstallUtil.exe and C:\Windows\Microsoft.NET\Framework64\v<version>\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)].

Windows
▸

Atomic Tests

8
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
powershellwindowsCheckIfInstallable 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. 
# 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
"@
}
powershellwindowsInstallHelper method call
Executes the InstallHelper class constructor runner instead of executing InstallUtil. Upon execution, no output will be displayed if the test executed successfuly. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

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

$CommandLine = "/logfile= /logtoconsole=false `"$InstallerAssemblyFullPath`""
$ExpectedOutput = 'Constructor_'

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

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs -MinimumViableAssembly

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
InstallHelper method execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}
powershellwindowsInstallUtil class constructor method call
Executes the installer assembly class constructor. Upon execution, version information will be displayed the .NET framework install utility. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

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

$CommandLine = "/logfile= /logtoconsole=false `"$InstallerAssemblyFullPath`""
$ExpectedOutput = 'Constructor_'

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

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs -MinimumViableAssembly

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
InstallUtil class constructor execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}
powershellwindowsInstallUtil Install method call
Executes the Install Method. Upon execution, version information will be displayed the .NET framework install utility. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

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

$CommandLine = "/logfile= /logtoconsole=false /installtype=notransaction /action=install `"$InstallerAssemblyFullPath`""
$ExpectedOutput = 'Constructor_Install_'

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

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
InstallUtil Install method execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}
powershellwindowsInstallUtil Uninstall method call - /U variant
Executes the Uninstall Method. Upon execution, version information will be displayed the .NET framework install utility. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

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

$CommandLine = "/logfile= /logtoconsole=false /U `"$InstallerAssemblyFullPath`""
$ExpectedOutput = 'Constructor_Uninstall_'

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

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
InstallUtil Uninstall method execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}
powershellwindowsInstallUtil Uninstall method call - '/installtype=notransaction /action=uninstall' variant
Executes the Uninstall Method. Upon execution, version information will be displayed the .NET framework install utility. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

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

$CommandLine = "/logfile= /logtoconsole=false /installtype=notransaction /action=uninstall `"$InstallerAssemblyFullPath`""
$ExpectedOutput = 'Constructor_Uninstall_'

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

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
InstallUtil Uninstall method execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}
powershellwindowsInstallUtil HelpText method call
Executes the Uninstall Method. Upon execution, help information will be displayed for InstallUtil. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

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

$CommandLine = "/? `"$InstallerAssemblyFullPath`""
$ExpectedOutput = 'Constructor_HelpText_'

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

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs

if ($ActualOutput -ne $ExpectedOutput) {
    throw @"
InstallUtil HelpText property execution test failure. Installer assembly execution output did not match the expected output.
Expected: $ExpectedOutput
Actual: $ActualOutput
"@
}
powershellwindowsInstallUtil evasive invocation
Executes an InstallUtil assembly by renaming InstallUtil.exe and using a nonstandard extension for the assembly. Upon execution, "Running a transacted installation." will be displayed, along with other information about the opperation. "The transacted install has completed." will be displayed upon completion. 
# Import the required test harness function, Invoke-BuildAndInvokeInstallUtilAssembly
. "#{test_harness}"

$InstallerAssemblyDir = "$Env:windir\System32\Tasks"
$InstallerAssemblyFileName = 'readme.txt'
$InstallerAssemblyFullPath = Join-Path -Path $InstallerAssemblyDir -ChildPath $InstallerAssemblyFileName

$CommandLine = "readme.txt"
$ExpectedOutput = 'Constructor_'

# Explicitly set the directory so that a relative path to readme.txt can be supplied.
Set-Location "$Env:windir\System32\Tasks"

Copy-Item -Path "$([System.Runtime.InteropServices.RuntimeEnvironment]::GetRuntimeDirectory())InstallUtil.exe" -Destination "$Env:windir\System32\Tasks\notepad.exe"

$TestArgs = @{
    OutputAssemblyDirectory = $InstallerAssemblyDir
    OutputAssemblyFileName = $InstallerAssemblyFileName
    InvocationMethod = 'Executable'
    CommandLine = $CommandLine
    InstallUtilPath = "$Env:windir\System32\Tasks\notepad.exe"
}

$ActualOutput = Invoke-BuildAndInvokeInstallUtilAssembly @TestArgs -MinimumViableAssembly

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

Mitigations

2
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1038Execution Prevention

Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions.

Application Control
  • Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution.
  • Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.
xml"`) Script Blocking
  • Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources.
  • Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g.
, Set-ExecutionPolicy AllSigned) Executable Blocking
  • Use Case: Prevent execution of binaries from suspicious locations, such as %TEMP% or %APPDATA% directories.
  • Implementation: Block execution of .exe, .bat, or .ps1 files from user-writable directories.
Dynamic Analysis Prevention
  • Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time.
  • Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution.
M1042Disable or Remove Feature or Program

Disable or remove unnecessary and potentially vulnerable software, features, or services to reduce the attack surface and prevent abuse by adversaries. This involves identifying software or features that are no longer needed or that could be exploited and ensuring they are either removed or properly disabled.

Remove Legacy Software
  • Use Case: Disable or remove older versions of software that no longer receive updates or security patches (e.g., legacy Java, Adobe Flash).
  • Implementation: A company removes Flash Player from all employee systems after it has reached its end-of-life date.
Disable Unused Features
  • Use Case: Turn off unnecessary operating system features like SMBv1, Telnet, or RDP if they are not required.
  • Implementation: Disable SMBv1 in a Windows environment to mitigate vulnerabilities like EternalBlue.
Control Applications Installed by Users
  • Use Case: Prevent users from installing unauthorized software via group policies or other management tools.
  • Implementation: Block user installations of unauthorized file-sharing applications (e.g., BitTorrent clients) in an enterprise environment.
Remove Unnecessary Services
  • Use Case: Identify and disable unnecessary default services running on endpoints, servers, or network devices.
  • Implementation: Disable unused administrative shares (e.g., C$, ADMIN$) on workstations.
Restrict Add-ons and Plugins
  • Use Case: Remove or disable browser plugins and add-ons that are not needed for business purposes.
  • Implementation: Disable Java and ActiveX plugins in web browsers to prevent drive-by attacks.
◈

Detection Coverage

0/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) none
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
▣

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