GHSA-r3r2-35v9-v238 Briefcase: Windows MSI Installer Privilege Escalation via Insecure Directory Permissions

• PyPI briefcase: >= 0.3.0, < 0.3.26 → fixed in 0.3.26

Impact If a developer uses Briefcase to produce an Windows MSI installer for a project, and that project is installed for All Users (i.e., per-machine scope), the installation process creates an directory that inherits all the permissions of the parent directory. Depending on the location chosen by the installing user, this may allow a low privilege but authenticated user to replace or modify the binaries installed by the application. If an administrator then runs the altered binary, the binary will run with elevated privileges. Patches The problem is caused by the template used to generate the WXS file for Windows projects. It was fixed with the following PRs: • beeware/briefcase-windows-app-template#86 • beeware/briefcase-windows-VisualStudio-template#85 These patches have been backported to the templates used in Briefcase 0.3.26, 0.4.0, and 0.4.1. Re-running `briefcase create` on your Briefcase project will result in the updated templates being used. Workarounds The change from beeware/briefcase-windows-app-template#86 can be added to any existing Briefcase .wxs file generated by Briefcase 0.3.24 or later. Resources beeware/briefcase#2759 is a formal bug report of the problem.