Microsoft released just two security updates this week that patch three vulnerabilities in Windows, marking the beginning of the bug year with a relatively slow start, said researchers.

Just one of the three flaws is rated "critical," the highest ranking Microsoft uses, while the other two were tagged as "important" and "moderate," the next two steps in the company's four-stage scoring system.

MS08-001, the update that addresses two bugs in a trio of Windows' TCP/IP protocols, was the obvious pick for immediate deployment. "This is a classic kind of IP attack," said Andrew Storms, director of security operations at nCircle Inc. "All an attacker needs is a well-crafted multicast packet."

Amol Sarwate, manager of Qualys' vulnerability lab, agreed. "An attack doesn't require any user intervention," he said, "such as clicking on a link or opening an attachment. An attack only requires remotely sent packets."

The three vulnerable protocols patched by the update include IGMP (Internet Group Management Protocol), MLD (Multicast Listener Discovery) and ICMP (Internet Control Message Protocol). The first two are used in over-IP multicasting -- the classic example of that one-to-many technology is a webcast -- while the third, ICMP, is a maintenance protocol that manages more mundane things: network connectivity and routing.

Storms downplayed the threat posed by the bugs patched in MS08-001. "The good news is that many hosts don't have multicast [protocols] enabled, and the firewall blocks [their traffic]. So for any zero-day exploit, default Windows XP and Vista [installations] have already been mitigated." Even so, he recommended that administrators deploy the update as soon as possible.

Sarwate, on the other hand, considered the danger to be more significant. "The protocols can easily be enabled," he said. "Companies may have enabled them on client machines, especially IGMP for group management applications in mixed environments with both Unix and Windows systems."

As reported earlier Tuesday, the MS08-002 bulletin patched a privilege-elevation bug in the LSASS (Local Security Authority Subsystem Service) process within Windows 2000, XP and Server 2003.

Both Storms and Sarwate, however, also remarked on what was not included in Tuesday's batch: a fix for the Web Proxy Autodiscovery (WPAD) bug that Microsoft acknowledged a month ago. The WPAD vulnerability -- actually a flaw in how Windows PCs look up DNS information -- was originally patched in 1999 but resurfaced recently when a researcher pointed out that it had crept back into later versions of the operating system.

"If Microsoft acknowledges an issue, they usually fix it in the next patch cycle," noted Sarwate. "But it's not being addressed. I was sort of hoping it would be fixed in the January releases."

All in all, however, it wasn't a bad way for IT administrators and Windows users to start 2008. In comparison, January 2007 featured four security updates that patched 10 different vulnerabilities. "This is a fairly light load to begin the year," Sarwate said.

"But I think this will be a big year for patches," countered Storms. "Both of these [bulletins] today are well-representing trends. Researchers are looking into the past to see vulnerabilities [they can use] in the future.

"I expect we'll see more [graphics device interface] vulnerabilities in Windows this year, more [Windows Metafile Format] bugs and more file-parsing bugs in 2008," he predicted.

January's patches can be downloaded and installed via the Microsoft Update and Windows Update services, as well as through Windows Server Update Services.