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Description

This search is to detect a suspicious 7z process with commandline pointing to SMB network share. This technique was seen in CONTI LEAK tools where it use 7z to archive a sensitive files and place it in network share tmp folder. This search is a good hunting query that may give analyst a hint why specific user try to archive a file pointing to SMB user which is un usual.

  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-08-17
  • Author: Teoderick Contreras, Splunk
  • ID: 01d29b48-ff6f-11eb-b81e-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1560.001 Archive via Utility Collection
T1560 Archive Collected Data Collection
Kill Chain Phase
  • Exploitation
NIST
CIS20
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 ="7z.exe" OR Processes.process_name = "7za.exe" OR Processes.original_file_name = "7z.exe" OR Processes.original_file_name =  "7za.exe") AND (Processes.process="*\\C$\\*" OR Processes.process="*\\Admin$\\*" OR Processes.process="*\\IPC$\\*") by Processes.original_file_name Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process Processes.parent_process_id Processes.process_id  Processes.dest Processes.user 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `7zip_commandline_to_smb_share_path_filter`

Macros

The SPL above uses the following Macros:

:information_source: 7zip_commandline_to_smb_share_path_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
  • Processes.parent_process_name
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • 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 command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed 7z.exe may be used.

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 archive process $process_name$ with suspicious cmdline $process$ in host $dest$

: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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