Detectionmediumtest

Potential Direct Syscall of NtOpenProcess

Detects potential calls to NtOpenProcess directly from NTDLL.

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Christian Burkard (Nextron Systems), Tim SheltonCreated Wed Jul 28Updated Wed Dec 133f3f3506-1895-401b-9cc3-e86b16e630d0windows

Log Source

WindowsProcess Access

ProductWindows← raw: windows

CategoryProcess Access← raw: process_access

Events when a process opens a handle to another process, commonly used for credential dumping via LSASS.

Detection Logic

detection:
    selection:
        CallTrace|startswith: 'UNKNOWN'
    filter_main_vcredist:
        TargetImage|endswith: 'vcredist_x64.exe'
        SourceImage|endswith: 'vcredist_x64.exe'
    filter_main_generic:
        # Examples include "systeminfo", "backgroundTaskHost", "AUDIODG"
        SourceImage|contains:
            - ':\Program Files (x86)\'
            - ':\Program Files\'
            - ':\Windows\System32\'
            - ':\Windows\SysWOW64\'
            - ':\Windows\WinSxS\'
        TargetImage|contains:
            - ':\Program Files (x86)\'
            - ':\Program Files\'
            - ':\Windows\System32\'
            - ':\Windows\SysWOW64\'
            - ':\Windows\WinSxS\'
    filter_main_kerneltrace_edge:
        # Cases in which the CallTrace is just e.g. 'UNKNOWN(19290435374)' from Microsoft-Windows-Kernel-Audit-API-Calls provider
        Provider_Name: 'Microsoft-Windows-Kernel-Audit-API-Calls'
    filter_optional_vmware:
        TargetImage|endswith: ':\Windows\system32\systeminfo.exe'
        SourceImage|endswith: 'setup64.exe' # vmware
    filter_optional_cylance:
        SourceImage|endswith: ':\Windows\Explorer.EXE'
        TargetImage|endswith: ':\Program Files\Cylance\Desktop\CylanceUI.exe'
    filter_optional_amazon:
        SourceImage|endswith: 'AmazonSSMAgentSetup.exe'
        TargetImage|endswith: 'AmazonSSMAgentSetup.exe'
    filter_optional_vscode: # VsCode
        SourceImage|endswith: '\AppData\Local\Programs\Microsoft VS Code\Code.exe'
        TargetImage|endswith: '\AppData\Local\Programs\Microsoft VS Code\Code.exe'
    filter_optional_teams: # MS Teams
        TargetImage|endswith: '\AppData\Local\Microsoft\Teams\current\Teams.exe'
        SourceImage|endswith: '\AppData\Local\Microsoft\Teams\current\Teams.exe'
    filter_optional_discord: # Discord
        TargetImage|contains: '\AppData\Local\Discord\'
        TargetImage|endswith: '\Discord.exe'
    filter_optional_yammer:
        SourceImage|contains: '\AppData\Local\yammerdesktop\app-'
        SourceImage|endswith: '\Yammer.exe'
        TargetImage|contains: '\AppData\Local\yammerdesktop\app-'
        TargetImage|endswith: '\Yammer.exe'
        GrantedAccess: '0x1000'
    filter_optional_evernote:
        TargetImage|endswith: '\Evernote\Evernote.exe'
    filter_optional_adobe_acrobat:
        SourceImage|contains: ':\Program Files\Adobe\Acrobat DC\Acrobat\'
        SourceImage|endswith: '\AcroCEF.exe'
        TargetImage|contains: ':\Program Files\Adobe\Acrobat DC\Acrobat\'
        TargetImage|endswith: '\AcroCEF.exe'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*