signed_binary_proxy_execution_installutil.yml

name: Signed Binary Proxy Execution InstallUtil
id: 9482a314-43dc-11ec-a3c9-acde48001122
version: 1
date: '2021-11-12'
author: Michael Haag, Splunk
description: Adversaries may use InstallUtil to proxy execution of code through a
  trusted Windows utility.
narrative: 'InstallUtil is a command-line utility that allows for installation and
  uninstallation of resources by executing specific installer components specified
  in .NET binaries. InstallUtil is 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. \

  There are multiple ways to instantiate InstallUtil and they are all outlined within
  Atomic Red Team - https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.004/T1218.004.md.
  Two specific ways may be used and that includes invoking via  installer assembly
  class constructor through .NET and via InstallUtil.exe. \

  Typically, adversaries will utilize the most commonly found way to invoke via InstallUtil
  Uninstall method. \

  Note that parallel processes, and parent process, play a role in how InstallUtil
  is being used. In particular, a developer using InstallUtil will spawn from VisualStudio.
  Adversaries, will spawn from non-standard processes like Explorer.exe, cmd.exe or
  PowerShell.exe. It''s important to review the command-line to identify the DLL being
  loaded. \

  Parallel processes may also include csc.exe being used to compile a local `.cs`
  file. This file will be the input to the output. Developers usually do not build
  direct on the command shell, therefore this should raise suspicion.'
references:
- https://attack.mitre.org/techniques/T1218/004/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.004/T1218.004.md
tags:
  analytic_story: Signed Binary Proxy Execution InstallUtil
  category:
  - Adversary Tactics
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  usecase: Advanced Threat Detection