A security flaw in the way many Microsoft applications process JPEG images could allow an attacker to gain control over a computer running the software, Microsoft warns.
Any program that processes JPEG images could be vulnerable, Microsoft said in Security Bulletin MS04-028. To take advantage of the flaw, an attacker would have to persuade a user to open a specially crafted image file. The image could be hosted on a website, included in an email or Office document, or hosted on a local network, Microsoft says.
A wide range of Microsoft software is vulnerable, including various versions of its Windows and Office products. Additionally, applications created with Microsoft's Visual Studio developer tool or the.Net Framework and third party applications that distribute their own copy of the vulnerable JPEG parsing engine may also be vulnerable.
Along with the Security Bulletin, Microsoft made available software updates to correct the flaw in its products. The software maker also offers a tool to scan a PC for certain installed products that are known to contain the vulnerable JPEG image processing engine.
Microsoft rates the flaw "important' for many of its products, but "critical" for Outlook versions 2002 and 2003, Internet Explorer 6 with Service Pack 1, Windows XP and Windows XP with Service Pack 1, Windows Server 2003, and the .Net Framework 1.0 with Service Pack 2 and .Net Framework 1.1, according to the security bulletin.
In Microsoft's rating system for security issues, vulnerabilities that could allow a malicious internet worm to spread without any action required on the part of the user are rated critical. Issues that will not lead to the spread of a worm without any action taken by the user, but could still expose user data or threaten system resources, are rated important.
The JPEG flaw was reported privately to Microsoft and it was not disclosed prior to Tuesday's release of the warning and patches, the software maker says. There have been no reports of the issue being exploited, it says.
In addition to the JPEG issue, Microsoft on Tuesday as part of its monthly security patch release cycle warned of a flaw in the WordPerfect 5.x converter that it supplies as part of Office 2000, Office XP, Office 2003 and recent editions of its Works suite.
The WordPerfect converter flaw, which Microsoft rates "important", could allow an attacker to gain full control over a victim's PC, Microsoft says. A software patch is available for vulnerable products to fix the problem.