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Description

The following analytic detects the usage of a renamed 7-Zip executable using Sysmon data. It leverages the OriginalFileName field to identify instances where the 7-Zip process has been renamed. This activity is significant as attackers often rename legitimate tools to evade detection while staging or exfiltrating data. If confirmed malicious, this behavior could indicate data exfiltration attempts or other unauthorized data manipulation, potentially leading to significant data breaches or loss of sensitive information. Analysts should validate the legitimacy of the 7-Zip executable and investigate parallel processes for further suspicious activities.

  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-05-20
  • Author: Michael Haag, Splunk
  • ID: 4057291a-b8cf-11eb-95fe-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
  • DE.AE
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.original_file_name=7z*.exe AND Processes.process_name!=7z*.exe) 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_7_zip_filter`

Macros

The SPL above uses the following Macros:

:information_source: detect_renamed_7-zip_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

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Limited false positives, however this analytic will need to be modified for each environment if Sysmon is not used.

Associated Analytic Story

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 $user$.

: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