A LAND attack is a remote denial-of-service condition caused by sending a packet to a machine with the source host/port the same as the destination host/port. The LAND attack scenario was discussed in 1997 by Carnegie Mellon's CERT Coordination Center.
It has been found that a single LAND packet sent to a file server could cause Windows Explorer to freeze on all workstations connected to that server.
"Our initial investigation has revealed that this reported vulnerability cannot be used by an attacker to run malicious software on a computer. At this point, our analysis indicates the impact of a successful attack would be to cause the computer to perform sluggishly for a short period of time."
However, it has been noted that systems running the Windows Firewall, enabled by default on Windows XP SP2, are not impacted by this issue.