Home/CVE-2022-21991/Sigma rules
Sigma

Sigma rules for CVE-2022-21991

7 rules · scoped to cve · back to CVE-2022-21991
Direct rules mention this entity in their title or description. Related rules cover the techniques this entity is known to use.
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Detection rules

7 of 7
direct high
Renamed Visual Studio Code Tunnel Execution
Detects renamed Visual Studio Code tunnel execution. Attackers can abuse this functionality to establish a C2 channel
status test author Nasreddine Bencherchali (Nextron Systems) id 2cf29f11-e356-4f61-98c0-1bdb9393d6da license Sigma · DRL-1.1
view Sigma YAML 
title: Renamed Visual Studio Code Tunnel Execution
id: 2cf29f11-e356-4f61-98c0-1bdb9393d6da
status: test
description: Detects renamed Visual Studio Code tunnel execution. Attackers can abuse this functionality to establish a C2 channel
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://code.visualstudio.com/docs/remote/tunnels
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-09-28
modified: 2025-10-29
tags:
    - attack.command-and-control
    - attack.t1071.001
    - attack.t1219
logsource:
    category: process_creation
    product: windows
detection:
    selection_image_only_tunnel:
        OriginalFileName: null
        CommandLine|endswith: '.exe tunnel'
    selection_image_tunnel_args:
        CommandLine|contains|all:
            - '.exe tunnel'
            - '--accept-server-license-terms'
    selection_image_tunnel_service:
        CommandLine|contains|all:
            - 'tunnel '
            - 'service'
            - 'internal-run'
            - 'tunnel-service.log'
    selection_parent_tunnel:
        ParentCommandLine|endswith: ' tunnel'
        Image|endswith: '\cmd.exe'
        CommandLine|contains|all:
            - '/d /c '
            - '\servers\Stable-'
            - 'code-server.cmd'
    filter_main_parent_code:
        ParentImage|endswith:
            - '\code-tunnel.exe'
            - '\code.exe'
    filter_main_image_code:
        Image|endswith:
            - '\code-tunnel.exe'
            - '\code.exe'
    condition: (1 of selection_image_* and not 1 of filter_main_image_*) or (selection_parent_tunnel and not 1 of filter_main_parent_*)
falsepositives:
    - Unknown
level: high
direct medium
Network Connection Initiated To Visual Studio Code Tunnels Domain
Detects network connections to Visual Studio Code tunnel domains initiated by a process on a system. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
status test author Kamran Saifullah id 4b657234-038e-4ad5-997c-4be42340bce4 license Sigma · DRL-1.1
view Sigma YAML 
title: Network Connection Initiated To Visual Studio Code Tunnels Domain
id: 4b657234-038e-4ad5-997c-4be42340bce4
related:
    - id: 9501f8e6-8e3d-48fc-a8a6-1089dd5d7ef4 # Net Connection DevTunnels
      type: similar
    - id: b3e6418f-7c7a-4fad-993a-93b65027a9f1 # DNS VsCode
      type: similar
    - id: 1cb0c6ce-3d00-44fc-ab9c-6d6d577bf20b # DNS DevTunnels
      type: similar
status: test
description: |
    Detects network connections to Visual Studio Code tunnel domains initiated by a process on a system. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://cydefops.com/vscode-data-exfiltration
author: Kamran Saifullah
date: 2023-11-20
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1572
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        DestinationHostname|endswith: '.tunnels.api.visualstudio.com'
    condition: selection
falsepositives:
    - Legitimate use of Visual Studio Code tunnel will also trigger this.
level: medium
direct medium
Visual Studio Code Tunnel Remote File Creation
Detects the creation of file by the "node.exe" process in the ".vscode-server" directory. Could be a sign of remote file creation via VsCode tunnel feature
status test author Nasreddine Bencherchali (Nextron Systems) id 56e05d41-ce99-4ecd-912d-93f019ee0b71 license Sigma · DRL-1.1
view Sigma YAML 
title: Visual Studio Code Tunnel Remote File Creation
id: 56e05d41-ce99-4ecd-912d-93f019ee0b71
status: test
description: |
    Detects the creation of file by the "node.exe" process in the ".vscode-server" directory. Could be a sign of remote file creation via VsCode tunnel feature
references:
    - Internal Research
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-10-25
tags:
    - attack.command-and-control
logsource:
    category: file_event
    product: windows
detection:
    selection:
        Image|contains: '\servers\Stable-'
        Image|endswith: '\server\node.exe'
        TargetFilename|contains: '\.vscode-server\data\User\History\'
    condition: selection
falsepositives:
    - Unknown
level: medium
direct medium
DNS Query To Visual Studio Code Tunnels Domain
Detects DNS query requests to Visual Studio Code tunnel domains. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
status test author citron_ninja id b3e6418f-7c7a-4fad-993a-93b65027a9f1 license Sigma · DRL-1.1
view Sigma YAML 
title: DNS Query To Visual Studio Code Tunnels Domain
id: b3e6418f-7c7a-4fad-993a-93b65027a9f1
related:
    - id: 9501f8e6-8e3d-48fc-a8a6-1089dd5d7ef4 # Net Connection DevTunnels
      type: similar
    - id: 4b657234-038e-4ad5-997c-4be42340bce4 # Net Connection VsCode
      type: similar
    - id: 1cb0c6ce-3d00-44fc-ab9c-6d6d577bf20b # DNS DevTunnels
      type: similar
status: test
description: |
    Detects DNS query requests to Visual Studio Code tunnel domains. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://cydefops.com/vscode-data-exfiltration
author: citron_ninja
date: 2023-10-25
modified: 2023-11-20
tags:
    - attack.command-and-control
    - attack.t1071.001
logsource:
    product: windows
    category: dns_query
detection:
    selection:
        QueryName|endswith: '.tunnels.api.visualstudio.com'
    condition: selection
falsepositives:
    - Legitimate use of Visual Studio Code tunnel will also trigger this.
level: medium
direct medium
Visual Studio Code Tunnel Execution
Detects Visual Studio Code tunnel execution. Attackers can abuse this functionality to establish a C2 channel
status test author Nasreddine Bencherchali (Nextron Systems), citron_ninja id 90d6bd71-dffb-4989-8d86-a827fedd6624 license Sigma · DRL-1.1
view Sigma YAML 
title: Visual Studio Code Tunnel Execution
id: 90d6bd71-dffb-4989-8d86-a827fedd6624
status: test
description: Detects Visual Studio Code tunnel execution. Attackers can abuse this functionality to establish a C2 channel
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://code.visualstudio.com/docs/remote/tunnels
author: Nasreddine Bencherchali (Nextron Systems), citron_ninja
date: 2023-10-25
modified: 2025-10-29
tags:
    - attack.command-and-control
    - attack.t1071.001
    - attack.t1219
logsource:
    category: process_creation
    product: windows
detection:
    selection_only_tunnel:
        OriginalFileName: null
        CommandLine|endswith: '.exe tunnel'
    selection_tunnel_args:
        CommandLine|contains|all:
            - '.exe tunnel'
            - '--accept-server-license-terms'
    selection_parent_tunnel:
        ParentCommandLine|endswith: ' tunnel'
        Image|endswith: '\cmd.exe'
        CommandLine|contains|all:
            - '/d /c '
            - '\servers\Stable-'
            - 'code-server.cmd'
    condition: 1 of selection_*
falsepositives:
    - Legitimate use of Visual Studio Code tunnel
level: medium
direct medium
Visual Studio Code Tunnel Shell Execution
Detects the execution of a shell (powershell, bash, wsl...) via Visual Studio Code tunnel. Attackers can abuse this functionality to establish a C2 channel and execute arbitrary commands on the system.
status test author Nasreddine Bencherchali (Nextron Systems) id f4a623c2-4ef5-4c33-b811-0642f702c9f1 license Sigma · DRL-1.1
view Sigma YAML 
title: Visual Studio Code Tunnel Shell Execution
id: f4a623c2-4ef5-4c33-b811-0642f702c9f1
status: test
description: Detects the execution of a shell (powershell, bash, wsl...) via Visual Studio Code tunnel. Attackers can abuse this functionality to establish a C2 channel and execute arbitrary commands on the system.
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://code.visualstudio.com/docs/remote/tunnels
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-10-25
tags:
    - attack.command-and-control
    - attack.t1071.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|contains: '\servers\Stable-'
        ParentImage|endswith: '\server\node.exe'
        ParentCommandLine|contains: '.vscode-server' # Technically one can host its own local server instead of using the VsCode one. And that would probably change the name (requires further research)
    # Note: Child processes (ie: shells) can be whatever technically (with some efforts)
    selection_child_1:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        CommandLine|contains: '\terminal\browser\media\shellIntegration.ps1'
    selection_child_2:
        Image|endswith:
            - '\wsl.exe'
            - '\bash.exe'
    condition: selection_parent and 1 of selection_child_*
falsepositives:
    - Legitimate use of Visual Studio Code tunnel and running code from there
level: medium
direct medium
Visual Studio Code Tunnel Service Installation
Detects the installation of VsCode tunnel (code-tunnel) as a service.
status test author Nasreddine Bencherchali (Nextron Systems) id 30bf1789-379d-4fdc-900f-55cd0a90a801 license Sigma · DRL-1.1
view Sigma YAML 
title: Visual Studio Code Tunnel Service Installation
id: 30bf1789-379d-4fdc-900f-55cd0a90a801
status: test
description: Detects the installation of VsCode tunnel (code-tunnel) as a service.
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://code.visualstudio.com/docs/remote/tunnels
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-10-25
tags:
    - attack.command-and-control
    - attack.t1071.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains|all:
            - 'tunnel '
            - 'service'
            - 'internal-run'
            - 'tunnel-service.log'
    condition: selection
falsepositives:
    - Legitimate installation of code-tunnel as a service
level: medium
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