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Description

This analytic identifies commonly used command-line arguments used by rclone.exe to initiate a file transfer. Some arguments were negated as they are specific to the configuration used by adversaries. In particular, an adversary may list the files or directories of the remote file share using ls or lsd, which is not indicative of malicious behavior. During triage, at this stage of a ransomware event, exfiltration is about to occur or has already. Isolate the endpoint and continue investigating by review file modifications and parallel processes.

  • Type: TTP
  • Product: Splunk Behavioral Analytics
  • Datamodel: Endpoint_Processes
  • Last Updated: 2021-12-03
  • Author: Michael Haag, Splunk
  • ID: e8b74268-5454-11ec-a799-acde48001122

ATT&CK

ID Technique Tactic
T1020 Automated Exfiltration Exfiltration
1
2
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5
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8
| from read_ssa_enriched_events() 
| where "Endpoint_Processes" IN(_datamodels) 
| eval timestamp=parse_long(ucast(map_get(input_event, "_time"), "string", null)), cmd_line=ucast(map_get(input_event, "process"), "string", null), process_name=ucast(map_get(input_event, "process_name"), "string", null), process_path=ucast(map_get(input_event, "process_path"), "string", null), parent_process_name=ucast(map_get(input_event, "parent_process_name"), "string", null), event_id=ucast(map_get(input_event, "event_id"), "string", null) 
| where cmd_line IS NOT NULL AND process_name IS NOT NULL AND process_name="rclone.exe" AND (like (cmd_line, "%copy%") OR like (cmd_line, "%mega%")OR like (cmd_line, "%pcloud%") OR like (cmd_line, "%ftp%") OR like (cmd_line, "%--config%") OR like (cmd_line, "%--progress%") OR like (cmd_line, "%--no-check-certificate%") OR like (cmd_line, "%--ignore-existing%") OR like (cmd_line, "%--auto-confirm%") OR like (cmd_line, "%--transfers%") OR like (cmd_line, "%--multi-thread-streams%")) 
| eval start_time=timestamp, end_time=timestamp, entities=mvappend(ucast(map_get(input_event, "dest_user_id"), "string", null), ucast(map_get(input_event, "dest_device_id"), "string", null)) 
| eval body=create_map(["event_id", event_id, "cmd_line", cmd_line, "process_name", process_name, "parent_process_name", parent_process_name, "process_path", process_path]) 
| into write_ssa_detected_events();

Macros

The SPL above uses the following Macros:

Note that detect_rclone_command-line_usage_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
  • dest_device_id
  • process_name
  • parent_process_name
  • process_path
  • dest_user_id
  • process
  • cmd_line

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_Processess datamodel.

Known False Positives

False positives should be limited as this is restricted to the Rclone process name. Filter or tune the analytic as needed.

Associated Analytic story

Kill Chain Phase

  • Exfiltration

RBA

Risk Score Impact Confidence Message
35.0 50 70 An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest_device_id$ by user $dest_user_id$ attempting to connect to a remote cloud service to move files or folders.

Note that risk score is calculated base on the following formula: (Impact * Confidence)/100

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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