Detectionhightest

Outbound RDP Connections Over Non-Standard Tools

Detects Non-Standard tools initiating a connection over port 3389 indicating possible lateral movement. An initial baseline is required before using this utility to exclude third party RDP tooling that you might use.

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Launch

Markus NeisCreated Wed May 15Updated Fri Feb 09ed74fe75-7594-4b4b-ae38-e38e3fd2eb23windows

Log Source

WindowsNetwork Connection

ProductWindows← raw: windows

CategoryNetwork Connection← raw: network_connection

Events for outbound and inbound network connections including DNS resolution.

Detection Logic

detection:
    selection:
        DestinationPort: 3389
        Initiated: 'true'
    filter_main_mstsc:
        Image:
            - 'C:\Windows\System32\mstsc.exe'
            - 'C:\Windows\SysWOW64\mstsc.exe'
    filter_optional_dns:
        # Note: https://github.com/SigmaHQ/sigma/pull/2249
        Image: 'C:\Windows\System32\dns.exe'
        SourcePort: 53
        Protocol: 'udp'
    filter_optional_avast:
        Image|endswith:
            - '\Avast Software\Avast\AvastSvc.exe'
            - '\Avast\AvastSvc.exe'
    filter_optional_sysinternals_rdcman:
        Image|endswith: '\RDCMan.exe'
    filter_optional_chrome:
        Image: 'C:\Program Files\Google\Chrome\Application\chrome.exe'
    filter_optional_third_party:
        Image|endswith:
            - '\FSAssessment.exe'
            - '\FSDiscovery.exe'
            - '\MobaRTE.exe'
            - '\mRemote.exe'
            - '\mRemoteNG.exe'
            - '\Passwordstate.exe'
            - '\RemoteDesktopManager.exe'
            - '\RemoteDesktopManager64.exe'
            - '\RemoteDesktopManagerFree.exe'
            - '\RSSensor.exe'
            - '\RTS2App.exe'
            - '\RTSApp.exe'
            - '\spiceworks-finder.exe'
            - '\Terminals.exe'
            - '\ws_TunnelService.exe'
    filter_optional_thor:
        Image|endswith:
            - '\thor.exe'
            - '\thor64.exe'
    filter_optional_splunk:
        Image|startswith: 'C:\Program Files\SplunkUniversalForwarder\bin\'
    filter_optional_sentinel_one:
        Image|endswith: '\Ranger\SentinelRanger.exe'
    filter_optional_firefox:
        Image: 'C:\Program Files\Mozilla Firefox\firefox.exe'
    filter_optional_tsplus:  # Some RAS
        Image:
            - 'C:\Program Files\TSplus\Java\bin\HTML5service.exe'
            - 'C:\Program Files (x86)\TSplus\Java\bin\HTML5service.exe'
    filter_optional_null:
        Image: null
    filter_optional_empty:
        Image: ''
    filter_optional_unknown:
        Image: '<unknown process>'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*