This patch eliminates two vulnerabilities affecting the implementation of the RDP protocol: The first vulnerability involves the way in which session encryption is implemented in certain versions of RDP. All RDP implementations permit the data in an RDP session to be encrypted. However, in the versions of RDP that are included in Windows 2000 and Windows XP, the checksums for the plain-text session data are sent without themselves being encrypted. An attacker who can ""eavesdrop on"" and record an RDP session might be able to conduct a straightforward cryptanalytic attack against the checksums and recover the session traffic. The second vulnerability involves the way in which the RDP implementation in Windows XP handles data packets that are malformed in a particular way. When RDP receives such data packets, the Remote Desktop service stops working. When this problem occurs, Windows stops working correctly also. An attacker does not have to be authenticated on an affected computer to deliver packets of this type to an affected computer.