Hackers have published code that could let an attacker disable the Windows Firewall on certain Windows XP machines.
The code, which was posted on the Internet early Sunday morning, could be used to disable the Windows Firewall on a fully patched Windows XP PC that was running Windows' Internet Connection Service (ICS). This service allows Windows users to essentially turn their PC into a router and share their Internet connection with other computers on the local area network (LAN.) It is typically used by home and small-business users.
The attacker could send a malicious data packet to another PC using ICS that would cause the service to terminate. Because this service is connected to the Windows firewall, this packet would also cause the firewall to stop working, said Tyler Reguly, a research engineer at nCircle Network Security Inc., who has blogged about the issue.