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Description

The following analytic identifies a dns query to a known TOR proxy website. This technique was seen in several adversaries, threat actors and malware like AgentTesla to To disguise the source of its malicious traffic. adversaries may chain together multiple proxies. This Anomaly detection might be a good pivot for a process trying to download or use TOR proxies in a compromised host machine.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2022-09-16
  • Author: Teoderick Contreras, Splunk
  • ID: 4c2d198b-da58-48d7-ba27-9368732d0054

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1071.003 Mail Protocols Command And Control
T1071 Application Layer Protocol Command And Control
Kill Chain Phase
  • Command and Control
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`sysmon` EventCode=22 QueryName IN ("*.torproject.org", "www.theonionrouter.com") 
| stats count min(_time) as firstTime max(_time) as lastTime by Image QueryName QueryStatus ProcessId  Computer 
| rename Computer as dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_multi_hop_proxy_tor_website_query_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_multi_hop_proxy_tor_website_query_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
  • Image
  • QueryName
  • QueryStatus
  • ProcessId
  • dest

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name and sysmon eventcode = 22 dns query events from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

third party application may use this proxies if allowed in production environment. Filter is needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 a process $Image$ is having a dns query in a tor domain $QueryName$ in $dest$

: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

source | version: 1