Microsoft released two more critical patches on Tuesday - days after it released an emergency fix for a critical WMF vulnerability that has been exploited by hackers and virus writers. The two latest updates - which, unlike the WMF patch, came out as part of Microsoft's regular Patch Tuesday update cycle - fix a flaw in the way Microsoft Windows processes embedded web fonts (MS06-002) and a Microsoft Outlook and Microsoft Exchange Transport Neutral Encapsulation Format (TNEF) decoding vulnerability (MS06-003).

Exploitation of these vulnerabilities creates a means for hackers to execute arbitrary code or cause a denial of service on a vulnerable system. The earlier WMF vulnerability remains the easiest to exploit, but security vendors warn that the embedded web-forms flaw also caries a computer worm risk.

"The new MS06-002 Web Font vulnerability looks to be just as much of a problem as the WMF issue discovered last week. Once again, there is the opportunity for an attacker to use a spam HTML email or web page to impact users within an organisation. Failing to install the third critical security update released this month could compromise both your Microsoft Exchange email server and the Microsoft Outlook email client, once again, because of a file format problem that allows remote execution when decoding a hacked file."

Users are urged to apply the latest patches as soon as possible. "With an increasing trend in zero-day exploits, it is important for IT staff to plan ahead and really minimise the cycle time to get critical updates installed in a timely manner. Last year’s industry average of 30 days for organisations to deploy a patch from the time it is made available will clearly not be acceptable in the 2006 threat climate," Bentley added. ®

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