Source: http://packetstormsecurity.org/files/115908/sysret.rar

This is proof of concept code that demonstrates the Microsoft Windows kernel (Intel/x64) SYSRET vulnerability as described in MS12-042. The shellcode disables code signing and will grant NT SYSTEM privileges to a specified application or already running process.

Exploit-DB Mirror: https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/20861.rar