Detection: TOR Traffic

Updated Date: 2025-05-02 ID: ea688274-9c06-4473-b951-e4cb7a5d7a45 Author: David Dorsey, Bhavin Patel, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies allowed network traffic to The Onion Router (TOR), an anonymity network often exploited for malicious activities. It leverages data from Next Generation Firewalls, using the Network_Traffic data model to detect traffic where the application is TOR and the action is allowed. This activity is significant as TOR can be used to bypass conventional monitoring, facilitating hacking, data breaches, and illicit content dissemination. If confirmed malicious, this could lead to unauthorized access, data exfiltration, and severe compliance violations, compromising the integrity and security of the network.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Network_Traffic where All_Traffic.app=tor AND All_Traffic.action=allowed by All_Traffic.action All_Traffic.app All_Traffic.bytes All_Traffic.bytes_in All_Traffic.bytes_out All_Traffic.dest All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.dvc All_Traffic.protocol All_Traffic.protocol_version All_Traffic.src All_Traffic.src_ip All_Traffic.src_port All_Traffic.transport All_Traffic.user All_Traffic.vendor_product 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `drop_dm_object_name("All_Traffic")` 
6| `tor_traffic_filter`

Data Source

Name	Platform	Sourcetype	Source
Palo Alto Network Traffic	Network	`'pan:traffic'`	`'screenconnect_palo_traffic'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
tor_traffic_filter	`search *`

tor_traffic_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1090.003	Multi-hop Proxy	Command And Control

Command and Control

DE.CM

CIS 13

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

In order to properly run this search, Splunk needs to ingest data from Next Generation Firewalls like Palo Alto Networks Firewalls or other network control devices that mediate the traffic allowed into an environment. This is necessary so that the search can identify an 'action' taken on the traffic of interest. The search requires the Network_Traffic data model to be populated.

Known False Positives

None at this time

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Suspicious network traffic allowed using TOR has been detected from $src_ip$ to $dest_ip$

Risk Object	Risk Object Type	Risk Score	Threat Objects
src_ip	system	80	No Threat Objects

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`pan_tor_allowed`	`pan:traffic`
Integration	✅ Passing	Dataset	`pan_tor_allowed`	`pan:traffic`

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: GitHub | Version: 9