Detectionhightest

Cmd.EXE Missing Space Characters Execution Anomaly

Detects Windows command lines that miss a space before or after the /c flag when running a command using the cmd.exe. This could be a sign of obfuscation of a fat finger problem (typo by the developer).

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Launch

Florian Roth (Nextron Systems)Created Tue Aug 23Updated Mon Mar 06a16980c2-0c56-4de0-9a79-17971979efddwindows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection1:  # missing space before the /c
        CommandLine|contains:
            - 'cmd.exe/c'
            - '\cmd/c'  # just cmd/c would be prone to false positives
            - '"cmd/c'
            - 'cmd.exe/k'
            - '\cmd/k'  # just cmd/k would be prone to false positives
            - '"cmd/k'
            - 'cmd.exe/r'
            - '\cmd/r'  # just cmd/r would be prone to false positives
            - '"cmd/r'
    selection2: # special cases verified via Virustotal Enterprise search
        CommandLine|contains:
            - '/cwhoami'
            - '/cpowershell'
            - '/cschtasks'
            - '/cbitsadmin'
            - '/ccertutil'
            - '/kwhoami'
            - '/kpowershell'
            - '/kschtasks'
            - '/kbitsadmin'
            - '/kcertutil'
    selection3:  # missing space after the /c
        CommandLine|contains:
            - 'cmd.exe /c'
            - 'cmd /c'
            - 'cmd.exe /k'
            - 'cmd /k'
            - 'cmd.exe /r'
            - 'cmd /r'
    filter_generic:
        CommandLine|contains:
            - 'cmd.exe /c '
            - 'cmd /c '
            - 'cmd.exe /k '
            - 'cmd /k '
            - 'cmd.exe /r '
            - 'cmd /r '
    filter_fp:
        - CommandLine|contains: 'AppData\Local\Programs\Microsoft VS Code\resources\app\node_modules'
        - CommandLine|endswith: 'cmd.exe/c .'
        - CommandLine: 'cmd.exe /c'
    condition: 1 of selection* and not 1 of filter_*