A working exploit for the MS12-020 RDP flaw is now available on the Metasploit Framework. The exploit causes a denial-of-service condition on vulnerable machines. Researchers have been working on developing a working remote code execution exploit. Microsoft officials have said little more than to acknowledge that there seems to be a leak from somewhere within MAPP (Microsoft Active Protections Program) The company has not indicated whether that was on their end or from one of the MAPP members.
Source: https://threatpost.com/exploit-ms12-020-rdp-bug-moves-metasploit-032012/76346/