Microsoft confirmed a zero-day bug exists in Windows 7. This exploit for the company's new operating system was discovered by a Canadian security researcher last Wednesday, but Microsoft downplayed the problem, saying users can protect themselves by blocking two ports on their firewall.
Attacks could be aimed at any browser, not just Internet Explorer (IE), Microsoft warned. After tricking users into visiting a malicious site or a previously-compromised domain, hackers could feed them specially-crafted URIs (uniform resource identifier), and then crash their PCs with malformed SMB packets.
Microsoft said it may patch the problem, but didn't spell out a timetable or commit to an out-of-cycle update before the next regularly-scheduled Patch Tuesday of Dec. 8. Instead, the company suggested users block TCP ports 139 and 445 at the firewall. Doing so, however, would disable browsers as well as a host of critical services, including network file-sharing and IT group policies.