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Description

The following analytic identifies the use of Plink being utilized to proxy egress or laterally in an organization. The analytic is limited to specific Plink options on the command-line, including -R -L and -D which will have the remote and local IP address or port and -l for a username. Modify the options as seen fit for your organization.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-09-15
  • Author: Michael Haag, Splunk
  • ID: 8aac5e1e-0fab-4437-af0b-c6e60af23eed

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1572 Protocol Tunneling Command And Control
T1021.004 SSH Lateral Movement
Kill Chain Phase
  • Command and Control
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=plink.exe OR Processes.original_file_name=Plink Processes.process IN ("*-R *", "*-L *", "*-D *", "*-l *") 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_protocol_tunneling_with_plink_filter`

Macros

The SPL above uses the following Macros:

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

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 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.

Known False Positives

False positives may be present if the organization allows for SSH tunneling outbound or internally. Filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
56.0 70 80 An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to tunnel to a remote destination.

: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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