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Description

The following analytic identifies the Windows InstallUtil.exe binary loading vaultcli.dll and Samlib.dll. This technique may be used to execute code to bypassing application control and capture credentials by utilizing a tool like MimiKatz. \ 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: 2022-08-25
  • Author: Michael Haag, Mauricio Velazo, Splunk
  • ID: ccfeddec-43ec-11ec-b494-acde48001122

Annotations

ATT&CK

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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`sysmon` EventCode=7  parent_process_name=installutil.exe ImageLoaded IN ("*\\samlib.dll", "*\\vaultcli.dll") 
| stats count min(_time) as firstTime max(_time) as lastTime by Computer, parent_process_name, ImageLoaded, OriginalFileName, ProcessId 
| rename Computer as dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_installutil_credential_theft_filter`

Macros

The SPL above uses the following Macros:

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

Supported Add-on (TA)

List of Splunk Add-on’s tested to work with the analytic.

Required fields

List of fields required to use this analytic.

  • _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

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and module loads from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

Typically this will not trigger as by it's very nature InstallUtil does not need credentials. Filter as needed.

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 $user$ loading samlib.dll and vaultcli.dll to potentially capture credentials in memory.

: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

source | version: 3