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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.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-03-16
  • Author: Michael Haag, Splunk
  • ID: 4fbf9270-43da-11ec-9486-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1218.004 InstallUtil Defense Evasion
T1218 System Binary Proxy Execution Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
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| 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.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 dest parent_process_name process_name process_path process process_id dest_port C2 
| `windows_installutil_remote_network_connection_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_installutil_remote_network_connection_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.original_file_name
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_path
  • Processes.process_path
  • Processes.parent_process_id
  • Ports.process_guid
  • Ports.dest
  • Ports.dest_port

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes and Ports node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

Limited false positives should be present as InstallUtil is not typically used to download remote files. Filter as needed based on Developers requirements.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
80.0 80 100 An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ generating a remote download.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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