Process Initiated Network Connection To Ngrok Domain

Description

Detects an executable initiating a network connection to "ngrok" domains. Attackers were seen using this "ngrok" in order to store their second stage payloads and malware. While communication with such domains can be legitimate, often times is a sign of either data exfiltration by malicious actors or additional download.

Query · sigma

selection:
  Initiated: 'true'
  DestinationHostname|endswith:
  - .ngrok-free.app
  - .ngrok-free.dev
  - .ngrok.app
  - .ngrok.dev
  - .ngrok.io
condition: selection

Known false positives

  • Legitimate use of the ngrok service.
Raw source Process Initiated Network Connection To Ngrok Domain · Sigma
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Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: Process Initiated Network Connection To Ngrok Domain
id: 18249279-932f-45e2-b37a-8925f2597670
related:
    - id: 1d08ac94-400d-4469-a82f-daee9a908849
      type: similar
status: test
description: |
    Detects an executable initiating a network connection to "ngrok" domains.
    Attackers were seen using this "ngrok" in order to store their second stage payloads and malware.
    While communication with such domains can be legitimate, often times is a sign of either data exfiltration by malicious actors or additional download.
references:
    - https://ngrok.com/
    - https://ngrok.com/blog-post/new-ngrok-domains
    - https://www.virustotal.com/gui/file/cca0c1182ac114b44dc52dd2058fcd38611c20bb6b5ad84710681d38212f835a/
    - https://www.rnbo.gov.ua/files/2023_YEAR/CYBERCENTER/november/APT29%20attacks%20Embassies%20using%20CVE-2023-38831%20-%20report%20en.pdf
author: Florian Roth (Nextron Systems)
date: 2022-07-16
modified: 2025-07-30
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1572
    - attack.t1102
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        DestinationHostname|endswith:
            - '.ngrok-free.app'
            - '.ngrok-free.dev'
            - '.ngrok.app'
            - '.ngrok.dev'
            - '.ngrok.io'
    condition: selection
falsepositives:
    - Legitimate use of the ngrok service.
# Note: The level of this rule is related to your internal policy.
level: high

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