Detection: TOR Traffic

Updated Date: 2024-09-30 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.

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.src_ip All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.action 
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 icon 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 Proxy Command And Control
T1090.003 Multi-hop Proxy Command And Control
KillChainPhase.COMMAND_AND_CONTROL
NistCategory.DE_CM
Cis18Value.CIS_13
APT41
Blue Mockingbird
Cinnamon Tempest
CopyKittens
Earth Lusca
Fox Kitten
LAPSUS$
Magic Hound
MoustachedBouncer
POLONIUM
Sandworm Team
Turla
Volt Typhoon
Windigo
APT28
APT29
Ember Bear
FIN4
Inception
Leviathan
Volt Typhoon
ZIRCONIUM

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 Risk Score Impact Confidence
Suspicious network traffic allowed using TOR has been detected from $src_ip$ to $dest_ip$ 80 100 80
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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: 5