# InstallUtil

InstallUtil
Technique
ID T1118
Tactic Defense Evasion, Execution
Platform Windows
Permissions Required User
Data Sources Process monitoring, Process command-line parameters
Supports Remote No
Defense Bypassed Process whitelisting
Contributors Casey Smith, Travis Smith, Tripwire

InstallUtil is a command-line utility that allows for installation and uninstallation of resources by executing specific installer components specified in .NET binaries.1 InstallUtil is 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.exe is digitally signed by Microsoft.

Adversaries may use InstallUtil to proxy execution of code through a trusted Windows utility. InstallUtil may also be used to bypass process whitelisting through use of attributes within the binary that execute the class decorated with the attribute [System.ComponentModel.RunInstaller(true)].2

## Mitigation

InstallUtil may not be necessary within a given environment. Use application whitelisting configured to block execution of InstallUtil.exe if it is not required for a given system or network to prevent potential misuse by adversaries.

## Detection

Use process monitoring to monitor the execution and arguments of InstallUtil.exe. Compare recent invocations of InstallUtil.exe with prior history of known good arguments and executed binaries to determine anomalous and potentially adversarial activity. Command arguments used before and after the InstallUtil.exe invocation may also be useful in determining the origin and purpose of the binary being executed.

## References

1. ^
1. ^  [ Smith, C. (2016, August 17). Includes 5 Known Application Whitelisting/ Application Control Bypass Techniques in One File. Retrieved June 30, 2017.]