Excel Exploit Emerges

Joe Wilcox Symantec's Security Response Weblog reports the company has received malicious code capable of exploiting Microsoft's newest zero-day vulnerability.

The exploit drops a Trojan and opens a back door on the infected system that "may enable an attacker to gain remote access to your computer," wrote Amado Hidalgo in the blog post.

The malicious code appears to exploit "a bug on MSO.DLL," which is an Office shared library. While Office applications could be vulnerable, Symantec has only seen code that exploits Excel. "Fully patched versions of Office 2000, XP, and 2003 appear to be vulnerable to this exploit," Hidalgo wrote.

On Friday, Microsoft issued a security bulletin for the zero-day flaw, which is the fifth since December.

Symantec's post somewhat raises the urgency around the flaw, because the one exploit can drop a back-door Trojan onto an infected system. Trojans of this kind allow remote download of software onto an infected computer.

Microsoft isn't the only software vendor struggling to combat vulnerabilities. According to the U.S. Department of Homeland Security's National Vulnerability Database there were 6,604 software vulnerabilities in 2006, up from 4,869 vulnerabilities in 2005 and 2,357 and 1,257 in, respectively, 2004 and 2003.

Vulnerabilities and exploitable flaws are up for just about every software category. Additionally, risks posed by vulnerabilities are increasing in most categories.

However, incidents of unauthorized access have so far declined in 2006 compared with 2005. The data isn't final and is likely to change over the next month, which could reverse the trend.

The government database did not immediately provide access to zero-day vulnerabilities.

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