Detectionmediumexperimental

Windows AppX Deployment Full Trust Package Installation

Detects the installation of MSIX/AppX packages with full trust privileges which run with elevated privileges outside normal AppX container restrictions

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Launch
Michael Haag, Swachchhanda Shrawan Poudel (Nextron Systems)Created Mon Nov 03e54279c7-4910-4e2c-902c-c56a25b549f6windows
Log Source
Windowsappxdeployment-server
ProductWindows← raw: windows
Serviceappxdeployment-server← raw: appxdeployment-server
Detection Logic
Detection Logic6 selectors
detection:
    selection:
        EventID: 400
        HasFullTrust: true
    filter_main_legitpath:
        PackageSourceUri|startswith:
            - 'file:///C:/Program%20Files/'
            - 'file:///C:/Program%20Files%20(x86)/'
    filter_main_microsoft:
        - PackageSourceUri|startswith: 'https://go.microsoft.com/fwlink/?linkid'
        - PackageSourceUri|contains:
              - '.cdn.microsoft.com'
              - '.cdn.office.net/'
    filter_main_callerprocess:
        CallingProcess|startswith:
            - 'sysprep.exe'
            - 'svchost.exe,AppReadiness'
    filter_optional_x_update:
        PackageSourceUri|startswith: 'x-windowsupdate://'
    filter_optional_microsoftclient:
        PackageFullName|startswith: 'MicrosoftWindows.Client.'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
False Positives

Some legitimate applications installation which have been missed from filtering can generate fps, thus baselining and tuning is recommended before deploying to production

Rule Metadata
Rule ID
e54279c7-4910-4e2c-902c-c56a25b549f6
Status
experimental
Level
medium
Type
Detection
Created
Mon Nov 03
Path
rules/windows/builtin/appxdeployment_server/win_appxpackaging_server_full_trust_package_installation.yml
Raw Tags
attack.defense-evasionattack.executionattack.t1204.002attack.t1553.005
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