Communication To LocaltoNet Tunneling Service Initiated

Hunt Hypothesis

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

Detection Rule

Sigma (Original)

title: Communication To LocaltoNet Tunneling Service Initiated
id: 3ab65069-d82a-4d44-a759-466661a082d1
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: windows
detection:
    selection:
        DestinationHostname|endswith:
            - '.localto.net'
            - '.localtonet.com'
        Initiated: 'true'
    condition: selection
falsepositives:
    - Legitimate use of the LocaltoNet service.
level: high

KQL (Azure Sentinel)

imNetworkSession
| where (DstHostname endswith ".localto.net" or DstHostname endswith ".localtonet.com") and NetworkDirection =~ "true"

Required Data Sources

False Positive Guidance

• Legitimate use of the LocaltoNet service.

MITRE ATT&CK Context

• Tactic: Command and Control
• Technique: T1572 — T1572
• Technique: T1090 — T1090
• Technique: T1102 — T1102

References

• https://localtonet.com/documents/supported-tunnels
• https://cloud.google.com/blog/topics/threat-intelligence/unc3944-targets-saas-applications
• SigmaHQ Rule