Microsoft late on Friday confirmed that an unpatched vulnerability exists in Windows 7, but downplayed the problem, saying most users would be protected from attack by blocking two ports at the firewall.
In a security advisory, Microsoft acknowledged that a bug in SMB (Server Message Block), a Microsoft-made network file- and print-sharing protocol, could be used by attackers to cripple Windows 7 and Windows Server 2008 R2 machines.