Privilege Escalation via DACL Permissions Overwrite (CVE-2019-0841)

A vulnerability in Microsoft Edge allows an attacker to overwrite DACL permissions and gain privilege escalation. This is done by creating a directory and hardlink in the local appdata folder, which will write the DACL. The version of Microsoft Edge must be specified in the PoC (polarbear.exe) for the exploit to work.

Mitigation:

Microsoft has released a patch for this vulnerability. Users should update their Microsoft Edge version to the latest version.

Source

Exploit-DB raw data:

There is still a vuln in the code triggered by CVE-2019-0841

The bug that this guy found: https://krbtgt.pw/dacl-permissions-overwrite-privilege-escalation-cve-2019-0841/

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.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!IMPORTANT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!IMPORTANT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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 ~ https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/46938.zip