Detect InstallUtil in Splunk
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 is digitally signed by Microsoft and located in the .NET directories. InstallUtil may also bypass application control by using the [System.ComponentModel.RunInstaller(true)] attribute decorator pattern. Known users of this technique include Mustang Panda (Beacon stager), WhisperGate (Windows Defender disable), Chaes malware, Saint Bot, and the Covenant C2 framework.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1218 System Binary Proxy Execution
- Sub-technique
- T1218.004 InstallUtil
- Canonical reference
- https://attack.mitre.org/techniques/T1218/004/
SPL Detection Query
index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
(Image="*\\installutil.exe" OR ParentImage="*\\installutil.exe")
| eval SuspiciousPath=if(match(CommandLine, "(Temp|AppData|Downloads|Public|ProgramData|\\\\Users\\\\)"), 1, 0)
| eval SuspiciousParent=if(match(ParentImage, "(cmd|powershell|wscript|cscript|mshta|winword|excel)\.exe"), 1, 0)
| eval Uninstall=if(match(CommandLine, "(/u|/uninstall)"), 1, 0)
| eval SuspiciousChild=if(ParentImage="*\\installutil.exe" AND match(Image, "(cmd|powershell|wscript|cscript|rundll32|regsvr32|net)\.exe"), 1, 0)
| eval RiskScore=SuspiciousPath + SuspiciousParent + Uninstall + SuspiciousChild
| where RiskScore > 0 OR ParentImage="*\\installutil.exe"
| table _time, host, User, Image, CommandLine, ParentImage, ParentCommandLine, SuspiciousPath, SuspiciousParent, Uninstall, SuspiciousChild, RiskScore
| sort - _timeDetects InstallUtil.exe abuse using Sysmon Event ID 1. Scores events across indicators: suspicious file paths, scripting engine parents, /uninstall flag usage (triggers RunInstaller Uninstall method), and child process spawning. Any InstallUtil child process is automatically flagged as it should not occur in legitimate use.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legitimate .NET software installers that use InstallUtil.exe to register Windows services or COM components during installation
- Software development teams running InstallUtil to install or uninstall custom .NET components during testing
- IT deployment tools (SCCM, PDQ Deploy) using InstallUtil to deploy .NET-based applications
- Windows Setup and update processes that invoke InstallUtil for framework component registration
Other platforms for T1218.004
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1InstallUtil Execution from Temp Directory
Expected signal: Sysmon Event ID 1: installutil.exe with Temp path in command line, /logfile and /logtoconsole flags. Security Event ID 4688 for the process. Sysmon Event ID 7 (Image Load) for the DLL being loaded.
- Test 2InstallUtil with Uninstall Flag
Expected signal: Sysmon Event ID 1: installutil.exe with /u flag and temp path. Security Event ID 4688. The process will fail if the file doesn't exist or isn't a valid installer assembly, but the process creation event still fires.
- Test 3InstallUtil Invoked from PowerShell
Expected signal: Sysmon Event ID 1: powershell.exe followed by installutil.exe with ParentImage=powershell.exe. Both SuspiciousParent and SuspiciousPath indicators fire. Security Event ID 4688 for both processes.
References (7)
- https://attack.mitre.org/techniques/T1218/004/
- https://lolbas-project.github.io/lolbas/Binaries/Installutil/
- https://msdn.microsoft.com/en-us/library/50614e95.aspx
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.004/T1218.004.md
- https://unit42.paloaltonetworks.com/attackers-tactics-and-techniques-in-unsecured-docker-daemons-revealed/
- https://www.cybereason.com/blog/operation-cobalt-kitty-apt
- https://www.anomali.com/blog/mustang-panda-threat-actor-targets-minority-groups-journalists-and-activists
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