Network Connection Initiated To BTunnels Domains

Status: test
Severity: medium
Log source: category network_connection, product windows
Author: Kamran Saifullah
Source: github.com/SigmaHQ/sigma

Detects network connections to BTunnels domains initiated by a process on the system. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.

Known false positives

Legitimate use of BTunnels will also trigger this.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1572` Protocol Tunneling
Exfiltration	`T1567` Exfiltration Over Web Service

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 3: Network connection

Rule body

title: Network Connection Initiated To BTunnels Domains
id: 9e02c8ec-02b9-43e8-81eb-34a475ba7965
status: test
description: |
    Detects network connections to BTunnels domains initiated by a process on the system.
    Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
references:
    - https://defr0ggy.github.io/research/Utilizing-BTunnel-For-Data-Exfiltration/
author: Kamran Saifullah
date: 2024-09-13
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1572
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        DestinationHostname|endswith: '.btunnel.co.in'
    condition: selection
falsepositives:
    - Legitimate use of BTunnels will also trigger this.
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Initiated: 'true'
    DestinationHostname|endswith: '.btunnel.co.in'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`DestinationHostname`	ends_with	`.btunnel.co.in`	`field:"DestinationHostname" kind:ends_with value:".btunnel.co.in"`
`Initiated`	eq	`true` corpus 50 (sigma 50)	`field:"Initiated" kind:eq value:"true"`