Detection: Linux Ngrok Reverse Proxy Usage

Description

The following analytic detects the use of Ngrok on a Linux operating system. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line arguments associated with Ngrok. This activity is significant because Ngrok can be used by adversaries to establish reverse proxies, potentially bypassing network defenses. If confirmed malicious, this could allow attackers to create persistent, unauthorized access channels, facilitating data exfiltration or further exploitation of the compromised system.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=ngrok Processes.process IN ("*start*", "*--config*","*http*","*authtoken*", "*http*", "*tcp*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `linux_ngrok_reverse_proxy_usage_filter`

Data Source

Name Platform Sourcetype Source Supported App
Sysmon for Linux EventID 1 Linux icon Linux 'sysmon:linux' 'Syslog:Linux-Sysmon/Operational' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
linux_ngrok_reverse_proxy_usage_filter search *
linux_ngrok_reverse_proxy_usage_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
T1572 Protocol Tunneling Command And Control
T1090 Proxy Command And Control
T1102 Web Service Command And Control
KillChainPhase.COMMAND_AND_CONTROL
NistCategory.DE_AE
Cis18Value.CIS_10
Chimera
Cinnamon Tempest
Cobalt Group
FIN13
FIN6
Fox Kitten
Leviathan
Magic Hound
OilRig
APT41
Blue Mockingbird
Cinnamon Tempest
CopyKittens
Earth Lusca
Fox Kitten
LAPSUS$
Magic Hound
MoustachedBouncer
POLONIUM
Sandworm Team
Turla
Volt Typhoon
Windigo
APT32
EXOTIC LILY
Ember Bear
FIN6
FIN8
Fox Kitten
Gamaredon Group
Inception
LazyScripter
Mustang Panda
Rocke
TeamTNT
Turla

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 Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

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

False positives may be present if Ngrok is an authorized utility. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A reverse proxy was identified spawning from $parent_process_name$ - $process_name$ on endpoint $dest$ by user $user$. 50 50 100
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 Syslog:Linux-Sysmon/Operational sysmon:linux
Integration ✅ Passing Dataset Syslog:Linux-Sysmon/Operational sysmon:linux

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: 3