News

Critical Vulnerability Affects Most Windows Systems

• By Scott Bekker
• November 21, 2002

Microsoft warned users late Wednesday of a critical new vulnerability involving the Microsoft Data Access Components, a ubiquitous technology present on most Windows systems. Especially vulnerable are Web servers in the middle of three-tier architectures with a SQL Server database at the back end and most Internet Explorer users.

Microsoft also issued an unrelated cumulative patch for Internet Explorer.

The critical vulnerability is a buffer overrun involving Remote Data Services (RDS), a component of MDAC. Microsoft describes MDAC as providing underlying functionality for a number of database operations. An unchecked buffer in a function called the RDS Data Stub permits an attacker to use a specially malformed HTTP request to cause a heap overrun. A sophisticated attack could result in the attacker to execute code on the target machine.

"Web server administrators should either install the patch, disable MDAC and/or RDS, or upgrade to MDAC 2.7, which is not affected by the vulnerability. Web client users should install the patch immediately on any system that is used for Web browsing," Microsoft's bulletin warns.

What makes the vulnerability especially serious for Internet Explorer is that the RDS Data Stub is included with all current versions of IE and there is no option to disable it. To exploit the vulnerability, an attacker would need to lure a user to a Web page that would send an HTTP reply to the user that would overrun the buffer.

A patch is available at www.microsoft.com/technet/security/bulletin/ms02-065.asp.

The separate cumulative Internet Explorer patch fixes six newly discovered vulnerabilities. It can be found at www.microsoft.com/technet/security/bulletin/ms02-066.asp.