Microsoft last week patched three vulnerabilities in the Server Message Block (SMB) file-sharing protocol in Windows, including two that could make "Swiss cheese" out of enterprise networks, according to one researcher.
"This is super nasty," said Eric Schultze, chief technology officer at Shavlik Technologies, a maker of patch management tools.
Microsoft rated two of the bugs as "critical" and the third as "moderate." Schultze said the critical bugs are extremely dangerous because attackers can exploit them by simply sending malformed data to unpatched machines.
Andrew Storms, director of security operations at nCircle Network Security, speculated that the latest bugs were found by researchers using information disclosed in SMB fixes Microsoft released in October and November.
Microsoft last week also issued the first patch for the Windows 7 operating system beta it had released days earlier. That update fixes a flaw that shaves several seconds of audio from any edited MP3 file.
Microsoft acknowledged that it did not fix a known vulnerability in the SMB in Windows 7. A spokesman said the bug will be fixed in "the next public release for Windows 7."
The latest update also didn't include a SQL Server patch that was expected by some researchers.
Microsoft last month said that older versions of its SQL Server database contained a critical vulnerability and that attack code had been released. "I'm not sure what's happening. Until last week, we were all geared up for that fix," said Wolfgang Kandek, CTO at Qualys.
Meanwhile, F-Secure said that a worm that exploits a months-old Windows bug infected more than a million PCs in a 24-hour period last Tuesday and Wednesday. Overall, the security firm estimates that 3.5 million PCs have been compromised by the "Downadup" worm.
Based on scans of several hundred thousand Windows PCs, Qualys concluded that about 30 percent have not been patched. Microsoft, along with researchers at firms like Symantec and Panda Security, blamed lackadaisical patching for the infections.