WiX Burn-based bundles are vulnerable to binary hijack when run as SYSTEM

Summary

# Summary

Burn uses an unprotected C:\Windows\Temp directory to copy binaries and run them from there. This directory is not entirely protected against low privilege users.

# Details

When a bundle runs as SYSTEM user, Burn uses GetTempPathW which points to an insecure directory C:\Windows\Temp to drop and load multiple binaries. Standard users can hijack the binary before it's loaded in the application resulting in elevation of privileges.

``` icacls c:\windows\temp

BUILTIN\Users:(CI)(S,WD,AD,X) BUILTIN\Administrators:(F) BUILTIN\Administrators:(OI)(CI)(IO)(F) NT AUTHORITY\SYSTEM:(F) NT AUTHORITY\SYSTEM:(OI)(CI)(IO)(F) CREATOR OWNER:(OI)(CI)(IO)(F) ```

Built in users(non-administrators) have special permissions to this folder and can create files and write to this directory. While they do not have explicit read permissions, there is a way they can monitor the changes to this directory using ReadDirectoryChangesW API and thus figure out randomized folder names created inside this directory as wel

# PoC

PoC works against the against visual studio enterprise with update 3 installer

## Reproduction steps

As a standard user, run the poc. Mount the iso and run visual studio [installer ](https://myvs.download.prss.microsoft.com/dbazure/en_visual_studio_enterprise_2015_with_update_3_x86_x64_dvd_8923288.iso?t=8132cd54-4b83-4478-8b73-fd9eb93437bf&P1=1709239640&P2=601&P3=2&P4=iorgKPv%2bG8n2NANTPUVoB92rr8t3W4XM594%2f9BtQQJrYrr8SwxGDxV%2fj%2f2F6Ulto0bXrIaFoZUr4yV37YAsOZVpM29IMtQEO0673AbDVuTe93qDb6wb7xdlpZSse0LZURUwwIFw5cwHQS2ZtvkunXE0osgXtEBT2IzVbPwVH39%2fum854xb4e2Dp61wgNrMZcOLLluBbeA3KX1sP3mm7WAWXBvlFiQWEnTfR5XH5mlLyPy2qfqCXWCjl84jNX7uY%2bpLR1IbfeD2JlcIQNeW2QrvmmqRrRbGvvaCA97IaSjM16XcDqVjvAEGW3sWXUc7y%2fEf68WZIyT7iilaEDUvaqqA%3d%3d&su=1)as local system account. The PoC should hijack the the binaries dropped by vs installer and a child process "notepad.exe" will be running.

# Impact

This is an Elevation of Privilege Vulnerability where a low privileged user can hijack binaries in an unprotected path C:\Windows\Temp to elevate to the SYSTEM user privileges.