Software Engineering Institute

Microsoft Windows XP SP2 and Windows Server 2003 are vulnerable to a denial-of-service attack via a crafted TCP packet. The packet is spoofed in a manner such that the source and destination IP addresses are the same, the source and destination ports are the same, and the SYN flag is set. This type of attack is known as a LAND attack.

Upon receiving such a packet, Windows may become unresponsive for several seconds.

By sending a specially crafted TCP packet to a Windows machine, an attacker could cause excessive CPU usage on the target system. Repeated exploitation of this vulnerability could result in a sustained denial-of-service condition.

Apply a patch
Apply a patch as described in Microsoft Security Bulletin MS05-019.

Filter Network Traffic

Network firewall, Intrusion Detection and Prevention Systems, and packet filtering technology may be able to detect and block LAND attacks. If a perimeter network device is configured to drop incoming packets with source IP addresses that match addresses within the network, a remote attacker may not be able to exploit this vulnerability.