Communication To LocaltoNet Tunneling Service Initiated - Linux

Status: test
Severity: high
Log source: category network_connection, product linux
Author: Andreas Braathen (mnemonic.io)
Source: github.com/SigmaHQ/sigma

Detects an executable initiating a network connection to "LocaltoNet" tunneling sub-domains. LocaltoNet is a reverse proxy that enables localhost services to be exposed to the Internet. Attackers have been seen to use this service for command-and-control activities to bypass MFA and perimeter controls.

Known false positives

Legitimate use of the LocaltoNet service.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1090` Proxy `T1102` Web Service `T1572` Protocol Tunneling

Telemetry coverage

Platform	Record / event type
Linux	Event ID 3: Network connection

Rule body

title: Communication To LocaltoNet Tunneling Service Initiated - Linux
id: c4568f5d-131f-4e78-83d4-45b2da0ec4f1
status: test
description: |
    Detects an executable initiating a network connection to "LocaltoNet" tunneling sub-domains.
    LocaltoNet is a reverse proxy that enables localhost services to be exposed to the Internet.
    Attackers have been seen to use this service for command-and-control activities to bypass MFA and perimeter controls.
references:
    - https://localtonet.com/documents/supported-tunnels
    - https://cloud.google.com/blog/topics/threat-intelligence/unc3944-targets-saas-applications
author: Andreas Braathen (mnemonic.io)
date: 2024-06-17
tags:
    - attack.command-and-control
    - attack.t1572
    - attack.t1090
    - attack.t1102
logsource:
    category: network_connection
    product: linux
detection:
    selection:
        DestinationHostname|endswith:
            - '.localto.net'
            - '.localtonet.com'
        Initiated: 'true'
    condition: selection
falsepositives:
    - Legitimate use of the LocaltoNet service.
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    DestinationHostname|endswith:
        - '.localto.net'
        - '.localtonet.com'
    Initiated: 'true'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`DestinationHostname`	ends_with	`.localto.net` `.localtonet.com`	`field:"DestinationHostname" kind:ends_with`
`Initiated`	eq	`true`	`field:"Initiated" kind:eq value:"true"`