Sigma rule: Windows AppX Deployment Full Trust Package Installation

Rule

Title

Windows AppX Deployment Full Trust Package Installation

Status

experimental

Level

medium

Author

Michael Haag, Swachchhanda Shrawan Poudel (Nextron Systems)

Date

2025-11-03

File

rules/windows/builtin/appxdeployment_server/win_appxdeployment_server_full_trust_package_installation.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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

Log source

product

windows

service

appxdeployment-server

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 (as the rule lists them)

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

Tags

• attack.execution
• attack.defense-impairment
• attack.t1204.002
• attack.t1553.005

MITRE ATT&CK ids this rule names

• T1204.002
• T1553.005

References

• https://www.splunk.com/en_us/blog/security/msix-weaponization-threat-detection-splunk.html

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/appxdeployment_server/win_appxdeployment_server_full_trust_package_installation.yml