title: User Added to Remote Desktop Users Group
id: ffa28e60-bdb1-46e0-9f82-05f7a61cc06e
related:
    - id: ad720b90-25ad-43ff-9b5e-5c841facc8e5 # Admin groups
      type: similar
    - id: 10fb649c-3600-4d37-b1e6-56ea90bb7e09 # Privileged groups
      type: similar
status: test
description: Detects addition of users to the local Remote Desktop Users group via "Net" or "Add-LocalGroupMember".
references:
    - https://www.microsoft.com/security/blog/2021/11/16/evolving-trends-in-iranian-threat-actor-activity-mstic-presentation-at-cyberwarcon-2021/
author: Florian Roth (Nextron Systems)
date: 2021-12-06
modified: 2022-09-09
tags:
    - attack.initial-access
    - attack.persistence
    - attack.lateral-movement
    - attack.t1133
    - attack.t1136.001
    - attack.t1021.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_main:
        - CommandLine|contains|all:
              - 'localgroup '
              - ' /add'
        - CommandLine|contains|all:
              - 'Add-LocalGroupMember '
              - ' -Group '
    selection_group:
        CommandLine|contains:
            - 'Remote Desktop Users'
            - 'Utilisateurs du Bureau à distance' # French for "Remote Desktop Users"
            - 'Usuarios de escritorio remoto' # Spanish for "Remote Desktop Users"
    condition: all of selection_*
falsepositives:
    - Administrative activity
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

title: Potential Remote Desktop Tunneling
id: 8a3038e8-9c9d-46f8-b184-66234a160f6f
status: test
description: Detects potential use of an SSH utility to establish RDP over a reverse SSH Tunnel. This can be used by attackers to enable routing of network packets that would otherwise not reach their intended destination.
references:
    - https://www.elastic.co/guide/en/security/current/potential-remote-desktop-tunneling-detected.html
author: Tim Rauch, Elastic (idea)
date: 2022-09-27
tags:
    - attack.lateral-movement
    - attack.t1021
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: ':3389' # RDP port and usual SSH tunneling related switches in command line
    selection_opt:
        CommandLine|contains:
            - ' -L '
            - ' -P '
            - ' -R '
            - ' -pw '
            - ' -ssh '
    condition: all of selection*
falsepositives:
    - Unknown
level: medium

title: New Remote Desktop Connection Initiated Via Mstsc.EXE
id: 954f0af7-62dd-418f-b3df-a84bc2c7a774
status: test
description: |
    Detects the usage of "mstsc.exe" with the "/v" flag to initiate a connection to a remote server.
    Adversaries may use valid accounts to log into a computer using the Remote Desktop Protocol (RDP). The adversary may then perform actions as the logged-on user.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1021.001/T1021.001.md#t1021001---remote-desktop-protocol
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/mstsc
author: frack113
date: 2022-01-07
modified: 2024-06-04
tags:
    - attack.lateral-movement
    - attack.t1021.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\mstsc.exe'
        - OriginalFileName: 'mstsc.exe'
    selection_cli:
        CommandLine|contains|windash: ' /v:'
    filter_optional_wsl:
        # Example: mstsc.exe /v:XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX /hvsocketserviceid:XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX /silent /wslg /plugin:WSLDVC /wslgsharedmemorypath:WSL\XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\wslg C:\ProgramData\Microsoft\WSL\wslg.rdp
        ParentImage: 'C:\Windows\System32\lxss\wslhost.exe'
        CommandLine|contains: 'C:\ProgramData\Microsoft\WSL\wslg.rdp'
    condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
    - WSL (Windows Sub System For Linux)
level: medium

title: Denied Access To Remote Desktop
id: 8e5c03fa-b7f0-11ea-b242-07e0576828d9
status: test
description: |
  This event is generated when an authenticated user who is not allowed to log on remotely attempts to connect to this computer through Remote Desktop.
  Often, this event can be generated by attackers when searching for available windows servers in the network.
references:
    - https://www.ultimatewindowssecurity.com/securitylog/encyclopedia/event.aspx?eventid=4825
author: Pushkarev Dmitry
date: 2020-06-27
modified: 2021-11-27
tags:
    - attack.lateral-movement
    - attack.t1021.001
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID: 4825
    condition: selection
falsepositives:
    - Valid user was not added to RDP group
level: medium

title: Potential Remote Desktop Connection to Non-Domain Host
id: ce5678bb-b9aa-4fb5-be4b-e57f686256ad
status: test
description: Detects logons using NTLM to hosts that are potentially not part of the domain.
references:
    - n/a
author: James Pemberton
date: 2020-05-22
modified: 2021-11-27
tags:
    - attack.command-and-control
    - attack.t1219.002
logsource:
    product: windows
    service: ntlm
    definition: Requires events from Microsoft-Windows-NTLM/Operational
detection:
    selection:
        EventID: 8001
        TargetName|startswith: 'TERMSRV'
    condition: selection
falsepositives:
    - Host connections to valid domains, exclude these.
    - Host connections not using host FQDN.
    - Host connections to external legitimate domains.
level: medium