Microsoft this week quietly fixed a security weakness in the configuration of the built-in firewall component of Windows XP.
The firewall - turned on by default by XP Service Pack 2 (SP2) - can leave files open across the whole net if users choose to enable file and printer sharing, it transpires. Such access should be restricted across a local network but Microsoft has implemented the feature in such a way that, for users of some dial-up ISPs, a local sub-net becomes the whole internet. Microsoft first informed users of this back in September but it has taken three months for it to release a fix.
Configuration changes released through Windows Update this week narrow the scope of what is defined as a local network. This update was issued at the same time as Microsoft's monthly patch roundup earlier this week but treated separately by Redmond (insecure configuration settings and security bugs been different beasties, at least according to Microsoft). Microsoft defines the update (more info here) as "critical".
In other Windows security news, security firm Secunia warns of a flaw in IE that can be used to conduct cross-site scripting attacks. The firm has produced a test to illustrating how the unpatched vuln. might be harnessed in phishing attacks. Even fully patched systems running Windows XP SP2 and up to date versions of IE are potentially vulnerable. Secunia advises users concerned about the problem to deactivate ActiveX or to use an alternative browser. ®