League of Legends Screensaver – Unquoted Service Path Privilege Escalation
# Exploit Title: League of Legends Screensaver Unquoted Service Paths Conditional Privilege Escalation. # CVE-ID: NA # Date: 13/04/2016 # Exploit Author: Vincent Yiu # Contact: vysec.private@gmail.com # Vendor Homepage: http://www.leagueoflegends.com # Software Link: screensaver.euw.leagueoflegends.com/en_US # Version: MD5 Hash: 0C1B02079CA8BF850D59DD870BC09963 # Tested on: Windows 7 Professional x64 fully updated. 1. Description: The League of Legends installer would install the League of Legends screensaver along with a service. The service would be called 'lolscreensaver'. This particular service was misconfigured such that the service binary path was unquoted. When the screensaver is installed to 'C:\Riot Games', the issue is not exploitable. However, during the installation process, users are able to specify a directory to install to. When a user chooses to install this to say an external drive, this becomes exploitable. This was reported to Riot Games and has been rectified in the latest version. 2. Proof http://i.imgur.com/S2fuUKa.png 3. Exploit: Simply run 'sc qc lolscreensaver' and check for unquoted service path. If the path is unquoted, then check the permissions of each directory using space as a token. Eg. D:\My Games\Hidden Files\Super Secure\Riot Games\service\service.exe Do icacls on D:\, 'D:\My Games\', 'D:\My Games\Hidden Files\', 'D:\My Games\Hidden Files\Super Secure\'. If you are able to write files to any of these directories, it is exploitable. If 'D:\My Games\' is writable, to exploit this issue, place a binary to run as SYSTEM into the folder and named as 'Hidden.exe". This is released on exploit-db as a means to make users aware. There was no way to automatically install a patch or update to fix this issue. It is recommended that the screensaver is uninstalled and redownloaded from the official website where this issue is now resolved. |