Windows XP Service Pack 2 has a flaw that gives users a false sense of security - quite literally. One report describes the security hole as a 'crater'. The vulnerability lies in the web systems management interface (WBEM), which allows downloadable code to spoof firewall status information.
It's a convoluted exploit, but in theory, a rogue application could wait until the firewall is down and then generate false system information indicating that the firewall is in fact up and working. That's because the WMI database - Microsoft's implementation of WBEM - is set to read/write, not read-only, reports eWeek. The magazine's labs used a simple script to generate false firewall status information.
No known malware uses this technique, but a mysterious communique signed by malware authors in 144 countries vowed not to use the latest exploit regarding it as "unethical" and "unnecessarily disruptive".
Of course we made that last part up. More usefully, if system administrators have a way of locking down the WMI database, we'll pass it right along to you. On Friday, the first Internet Explorer vulnerability of the SP2 era was discovered. ®