LoFP / limited false positives should be present as installutil is not typically used to download remote files. filter as needed based on developers requirements.

Techniques

• T1218
• T1218.004

Sample rules

Windows InstallUtil Uninstall Option with Network

• source: splunk
• technicques:
  • T1218.004
  • T1218

Description

The following analytic identifies the Windows InstallUtil.exe binary making a remote network connection. This technique may be used to download and execute code while bypassing application control using the /u (uninstall) switch. InstallUtil uses the functions install and uninstall within the System.Configuration.Install namespace to process .net assembly. Install function requires admin privileges, however, uninstall function can be run as an unprivileged user. When InstallUtil.exe is used in a malicous manner, the path to an executable on the filesystem is typically specified. Take note of the parent process. In a suspicious instance, this will be spawned from a non-standard process like Cmd.exe, PowerShell.exe or Explorer.exe. If used by a developer, typically this will be found with multiple command-line switches/arguments and spawn from Visual Studio. During triage review resulting network connections, file modifications, and parallel processes. Capture any artifacts and review further.

Detection logic

| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where `process_installutil` Processes.process IN ("*/u*", "*uninstall*") by _time span=1h  Processes.user Processes.process_id Processes.process_name Processes.dest Processes.process_path Processes.process Processes.parent_process_name 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| join  process_id [
| tstats `security_content_summariesonly` count FROM datamodel=Network_Traffic.All_Traffic where All_Traffic.dest_port != 0 by All_Traffic.process_id All_Traffic.dest All_Traffic.dest_port 
| `drop_dm_object_name(All_Traffic)` 
| rename dest as C2 ] 
| table _time user dest parent_process_name process_name process_path process process_id dest_port C2 
| `windows_installutil_uninstall_option_with_network_filter`

Windows InstallUtil Remote Network Connection

• source: splunk
• technicques:
  • T1218.004
  • T1218

Description

The following analytic identifies the Windows InstallUtil.exe binary making a remote network connection. This technique may be used to download and execute code while bypassing application control. When InstallUtil.exe is used in a malicous manner, the path to an executable on the filesystem is typically specified. Take note of the parent process. In a suspicious instance, this will be spawned from a non-standard process like Cmd.exe, PowerShell.exe or Explorer.exe. If used by a developer, typically this will be found with multiple command-line switches/arguments and spawn from Visual Studio. During triage review resulting network connections, file modifications, and parallel processes. Capture any artifacts and review further.

Detection logic

| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where `process_installutil` by _time span=1h  Processes.process_id Processes.process_name Processes.dest Processes.user Processes.process_path Processes.process Processes.parent_process_name Processes.original_file_name 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| join  process_id [
| tstats `security_content_summariesonly` count FROM datamodel=Network_Traffic.All_Traffic where All_Traffic.dest_port != 0 by All_Traffic.process_id All_Traffic.dest All_Traffic.dest_port 
| `drop_dm_object_name(All_Traffic)` 
| rename dest as C2 ] 
| table _time user dest parent_process_name process_name process_path process process_id dest_port C2 
| `windows_installutil_remote_network_connection_filter`

Windows InstallUtil URL in Command Line

• source: splunk
• technicques:
  • T1218.004
  • T1218

Description

The following analytic identifies the Windows InstallUtil.exe binary passing a HTTP request on the command-line. This technique may be used to download and execute code while bypassing application control. When InstallUtil.exe is used in a malicous manner, the path to an executable on the filesystem is typically specified. Take note of the parent process. In a suspicious instance, this will be spawned from a non-standard process like Cmd.exe, PowerShell.exe or Explorer.exe. If used by a developer, typically this will be found with multiple command-line switches/arguments and spawn from Visual Studio. During triage review resulting network connections, file modifications, and parallel processes. Capture any artifacts and review further.

Detection logic

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_installutil` Processes.process IN ("*http://*","*https://*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_installutil_url_in_command_line_filter`