title: Communication To Ngrok Tunneling Service - Linux
id: 19bf6fdb-7721-4f3d-867f-53467f6a5db6
status: test
description: Detects an executable accessing an ngrok tunneling endpoint, which could be a sign of forbidden exfiltration of data exfiltration by malicious actors
references:
    - https://twitter.com/hakluke/status/1587733971814977537/photo/1
    - https://ngrok.com/docs/secure-tunnels/tunnels/ssh-reverse-tunnel-agent
author: Florian Roth (Nextron Systems)
date: 2022-11-03
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1568.002
    - attack.t1572
    - attack.t1090
    - attack.t1102
    - attack.s0508
logsource:
    product: linux
    category: network_connection
detection:
    selection:
        DestinationHostname|contains:
            - 'tunnel.us.ngrok.com'
            - 'tunnel.eu.ngrok.com'
            - 'tunnel.ap.ngrok.com'
            - 'tunnel.au.ngrok.com'
            - 'tunnel.sa.ngrok.com'
            - 'tunnel.jp.ngrok.com'
            - 'tunnel.in.ngrok.com'
    condition: selection
falsepositives:
    - Legitimate use of ngrok
level: high

title: Communication To Ngrok Tunneling Service Initiated
id: 1d08ac94-400d-4469-a82f-daee9a908849
related:
    - id: 18249279-932f-45e2-b37a-8925f2597670
      type: similar
status: test
description: |
    Detects an executable initiating a network connection to "ngrok" tunneling 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://twitter.com/hakluke/status/1587733971814977537/photo/1
    - https://ngrok.com/docs/secure-tunnels/tunnels/ssh-reverse-tunnel-agent
author: Florian Roth (Nextron Systems)
date: 2022-11-03
modified: 2024-02-02
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1568.002
    - attack.t1572
    - attack.t1090
    - attack.t1102
    - attack.s0508
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        DestinationHostname|contains:
            - 'tunnel.us.ngrok.com'
            - 'tunnel.eu.ngrok.com'
            - 'tunnel.ap.ngrok.com'
            - 'tunnel.au.ngrok.com'
            - 'tunnel.sa.ngrok.com'
            - 'tunnel.jp.ngrok.com'
            - 'tunnel.in.ngrok.com'
    condition: selection
falsepositives:
    - Legitimate use of the ngrok service.
level: high

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

title: PUA - Ngrok Execution
id: ee37eb7c-a4e7-4cd5-8fa4-efa27f1c3f31
status: test
description: |
  Detects the use of Ngrok, a utility used for port forwarding and tunneling, often used by threat actors to make local protected services publicly available.
  Involved domains are bin.equinox.io for download and *.ngrok.io for connections.
references:
    - https://ngrok.com/docs
    - https://www.fireeye.com/blog/threat-research/2021/05/shining-a-light-on-darkside-ransomware-operations.html
    - https://stackoverflow.com/questions/42442320/ssh-tunnel-to-ngrok-and-initiate-rdp
    - https://www.virustotal.com/gui/file/58d21840d915aaf4040ceb89522396124c82f325282f805d1085527e1e2ccfa1/detection
    - https://cybleinc.com/2021/02/15/ngrok-platform-abused-by-hackers-to-deliver-a-new-wave-of-phishing-attacks/
    - https://twitter.com/xorJosh/status/1598646907802451969
    - https://www.softwaretestinghelp.com/how-to-use-ngrok/
author: Florian Roth (Nextron Systems)
date: 2021-05-14
modified: 2023-02-21
tags:
    - attack.command-and-control
    - attack.t1572
logsource:
    category: process_creation
    product: windows
detection:
    selection1:
        CommandLine|contains:
            - ' tcp 139'
            - ' tcp 445'
            - ' tcp 3389'
            - ' tcp 5985'
            - ' tcp 5986'
    selection2:
        CommandLine|contains|all:
            - ' start '
            - '--all'
            - '--config'
            - '.yml'
    selection3:
        Image|endswith: 'ngrok.exe'
        CommandLine|contains:
            - ' tcp '
            - ' http '
            - ' authtoken '
    selection4:
        CommandLine|contains:
            - '.exe authtoken '
            - '.exe start --all'
    condition: 1 of selection*
falsepositives:
    - Another tool that uses the command line switches of Ngrok
    - Ngrok http 3978 (https://learn.microsoft.com/en-us/azure/bot-service/bot-service-debug-channel-ngrok?view=azure-bot-service-4.0)
level: high

title: Ngrok Usage with Remote Desktop Service
id: 64d51a51-32a6-49f0-9f3d-17e34d640272
status: test
description: Detects cases in which ngrok, a reverse proxy tool, forwards events to the local RDP port, which could be a sign of malicious behaviour
references:
    - https://twitter.com/tekdefense/status/1519711183162556416?s=12&t=OTsHCBkQOTNs1k3USz65Zg
    - https://ngrok.com/
author: Florian Roth (Nextron Systems)
date: 2022-04-29
tags:
    - attack.command-and-control
    - attack.t1090
logsource:
    product: windows
    service: terminalservices-localsessionmanager
detection:
    selection:
        EventID: 21
        Address|contains: '16777216'
    condition: selection
falsepositives:
    - Unknown
level: high