Conficker, which began hitting Windows PCs in November 2008, infected millions of machines in the next few months, and caused a media frenzy in April 2009 when the massive collection of compromised computers was to receive a new malware update, also exploited an SMB flaw.
Even though Microsoft had rushed out an emergency patch before Conficker appeared, the worm still spread widely and wildly.
"I don't know which is worse, MS11-018 or MS11-020," said Storms. "But the SMB bug is a worm kind of vulnerability. It has the makings of another Conficker."
Assuming an attacker can plant malware on a single PC -- not difficult when people carelessly click on links -- he could use the SMB bug patched in MS11-020 to spread a worm to other machines on the same network.
"We learned a lot from Conficker," said Storms. "It led us to not believe that the sky is falling when people said so, but it also tells us that you need to install this patch right away."
MS11-019, another update that focused on the SMB protocol, was Bryant's third priority pick.
The company also issued patches for Excel, PowerPoint, .Net and multiple bits and pieces of Windows.
In the last category, MS11-034 patched 30 vulnerabilities -- nearly half the total and a record for a single update -- in the Windows kernel device driver. All 30 were reported to Microsoft by Tarjei Mandt, a researcher who works for Norman ASA, a Norwegian antivirus firm, who has numerous other kernel bugs on his resume.
"In the end, though, these are just elevation of privilege vulnerabilities," said Josh Abraham, security researcher at Rapid7. "From a penetration tester's perspective, which is what I do, let's just say they wouldn't be my main focus."
Microsoft issued a pair of security advisories today as well, each backed by a download users can retrieve and install.
The most notable of the two, said researchers, delivered a file validation security feature that debuted in Office 2010 to users running the older Office 2003 and Office 2007 application suites.
In December 2010, Microsoft announced it would backport file validation to Office 2003 and Office 2007, saying then that it would do so early this year.
Today's security patches can be downloaded and installed via the Microsoft Update and Windows Update services, as well as through Windows Server Update Services.
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