splunk-security_content/docs/_posts/2021-09-16-detect_renamed_psexec.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Detect Renamed PSExec	System Services, Service Execution	Endpoint	2021-09-16	true		System Services Execution Service Execution Execution Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

The following analytic identifies renamed instances of PsExec.exe being utilized on an endpoint. Most instances, it is highly probable to capture Psexec.exe or other SysInternal utility usage with the command-line argument of -accepteula. During triage, validate this is the legitimate version of PsExec by reviewing the PE metadata. In addition, review parallel processes for further suspicious behavior.

• Type: Hunting
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-09-16
• Author: Michael Haag, Splunk
• ID: 683e6196-b8e8-11eb-9a79-acde48001122

ATT&CK

ID	Technique	Tactic
T1569	System Services	Execution

| T1569.002 | Service Execution | Execution |

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_psexec` by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.original_file_name 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `detect_renamed_psexec_filter`

Associated Analytic Story

• SamSam Ransomware
• DHS Report TA18-074A
• HAFNIUM Group
• DarkSide Ransomware
• Active Directory Lateral Movement

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 node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

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

Kill Chain Phase

• Exploitation
• Lateral Movement
• Execution

Known False Positives

Limited false positives should be present. It is possible some third party applications may use older versions of PsExec, filter as needed.

RBA

Risk Score	Impact	Confidence	Message
27.0	30	90	The following process_name has been identified as renamed, spawning from parent_process_name on dest by user.

Reference

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1569.002/T1569.002.yaml
• https://redcanary.com/blog/threat-hunting-psexec-lateral-movement/

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1569.002/atomic_red_team/windows-sysmon.log

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