The ZOTOB worm appeared soon after Microsoft warned of the three new critical security flaws, which the latest Windows Update had supposedly fixed. The new worm uses holes in the security of Windows 95 all the way through to XP and will allow malicious attackers access to your PC.

Security company Trend Micro said in a release, "hundreds of infection reports were sighted in the United States and Germany." Supposedly the infection is spreading, and quickly.

The worm burrows itself into your Windows system folder as BOTZOR.EXE and tinkers with the system host file to stop users from getting access to security websites. It can connect itself up to IRC and give attackers control over your system.

The big security companies are warning to leave your firewalls on high alert and to keep your anti-virus software updated.

SECURITY outfit Symantec is warning that it would be a doddle for hackers to adapt the Zotob worm to attack Windows XP.

David Cole, the director of Symantec's Security Response, told TechWeb news that although Zotob has been making mincemeat of unpatched Windows 2000 machines, it would be easy to adapt to Windows XP.

He said that if a hacker adds Windows XP capabilities to Zotob, a new wave of attacks could be made on home users and those in small- and mid-sized businesses.

However the victims would have not patched their systems for a while and even Cole admits there would be few that would fit the attack profile.

Symantec continued to recommend that users apply the patch to all systems, including all Windows XP and XP SP1 machines.