Detectionmediumtest

Potentially Suspicious Windows App Activity

Detects potentially suspicious child process of applications launched from inside the WindowsApps directory. This could be a sign of a rogue ".appx" package installation/execution

Convert In Phoenix Studio

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

Launch

Nasreddine Bencherchali (Nextron Systems)Created Thu Jan 12Updated Tue Oct 07f91ed517-a6ba-471d-9910-b3b4a398c0f3windows

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:
        # GrandParentImage|endswith: '\sihost.exe'
        ParentImage|contains: 'C:\Program Files\WindowsApps\'
    selection_susp_img:
        Image|endswith:
            # You can add more LOLBINs
            - '\cmd.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\powershell.exe'
            - '\powershell_ise.exe'
            - '\pwsh.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\wscript.exe'
    selection_susp_cli:
        # You can add more potentially suspicious keywords
        CommandLine|contains:
            - 'cmd /c'
            - 'Invoke-'
            - 'Base64'
    filter_optional_terminal:
        ParentImage|contains: ':\Program Files\WindowsApps\Microsoft.WindowsTerminal'
        ParentImage|endswith: '\WindowsTerminal.exe'
        # Note: to avoid FP add the default shells and profiles that your WT integrates
        Image|endswith:
            - '\powershell.exe'
            - '\cmd.exe'
            - '\pwsh.exe'
    filter_optional_sysinternals:
        ParentImage|startswith: 'C:\Program Files\WindowsApps\Microsoft.SysinternalsSuite'
        Image|endswith: '\cmd.exe'
    condition: selection_parent and 1 of selection_susp_* and not 1 of filter_optional_*