Detectionhightest

Suspicious ShellExec_RunDLL Call Via Ordinal

Detects suspicious call to the "ShellExec_RunDLL" exported function of SHELL32.DLL through the ordinal number to launch other commands. Adversary might only use the ordinal number in order to bypass existing detection that alert on usage of ShellExec_RunDLL on CommandLine.

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Launch

Swachchhanda Shrawan PoudelCreated Sun Dec 018823e85d-31d8-473e-b7f4-92da070f0fc6windows

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:
    selection_parent_img:
        ParentCommandLine|contains: 'SHELL32.DLL'
    selection_parent_ordinal:
        ParentCommandLine|contains:
            # Note: The ordinal number may differ depending on the DLL version
            # Example: rundll32 SHELL32.DLL,#572 "cmd.exe" "/c calc.exe"
            - '#568'
            - '#570'
            - '#572'
            - '#576'
    selection_susp_cli_parent:
        # Note: Add additional binaries and suspicious paths to increase coverage
        - ParentCommandLine|contains:
              - 'comspec'
              - 'iex'
              - 'Invoke-'
              - 'msiexec'
              - 'odbcconf'
              - 'regsvr32'
        - ParentCommandLine|contains:
              - '\Desktop\'
              - '\ProgramData\'
              - '\Temp\'
              - '\Users\Public\'
    selection_susp_child_img:
        Image|endswith:
            - '\bash.exe'
            - '\bitsadmin.exe'
            - '\cmd.exe'
            - '\cscript.exe'
            - '\curl.exe'
            - '\mshta.exe'
            - '\msiexec.exe'
            - '\msxsl.exe'
            - '\odbcconf.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\regsvr32.exe'
            - '\schtasks.exe'
            - '\wmic.exe'
            - '\wscript.exe'
    condition: all of selection_parent_* and 1 of selection_susp_*