Microsoft issues patch for serious security hole

[InfoSec News <isn () c4i org>]

http://www.nwfusion.com/news/2002/1120mspatch.html

By Paul Roberts
IDG News Service
11/20/02

Microsoft issued a software patch Wednesday for what it described as a
"critical" new security vulnerability affecting most versions of its
Windows operating systems and certain versions of the Internet
Explorer (IE) Web browser.

The security flaw affects the Microsoft Data Access Components (MDAC),
a collection of components that provide database access for Windows
platforms, according to a statement from Foundstone, a software
vulnerability management company in Mission Viejo, Calif., that
discovered the flaw.

The vulnerability involves what's known as an "unchecked buffer" in
the Remote Data Services (RDS) component of MDAC. The faulty code is
in a function called the RDS Data Stub which is used to pull
information from incoming HTTP requests and create RDS commands,
according to Microsoft.

An attacker could exploit the security weakness by sending an
improperly formatted HTTP (Hypertext Transfer Protocol) request to the
Data Stub that contained a surplus of data, causing the buffer to
overflow and the attacker's data to be placed and run on the affected
machine.

The vulnerability affects certain versions of Windows NT, Windows 2000
and Windows Me, Microsoft said, and potentially other versions of its
operating system. It said Windows XP users are not affected and need
take no action.

The vulnerability received a severity rating of "critical" from
Microsoft, the highest possible rating under the company's new
vulnerability rating system, which was announced Tuesday. Microsoft
defines critical vulnerabilities as those "whose exploitation could
allow the propagation of an Internet worm such as Code Red or Nimda
without user action."

The security hole is particularly menacing because of the large number
of systems that are vulnerable to it and because of the ease with
which existing worms such as Code Red or Nimda could be modified to
take advantage of the newly disclosed flaw, said Stuart McClure,
Foundstone's president and CTO.

"What makes it really quite dangerous is that it can be easily added
to a worm," McClure said.

"It's very much in line with Code Red and Nimda because of the attack
vectors and the ways that it attacks. But with this vulnerability both
the server and client component can be attacked, as opposed to Code
Red and Nimda, which basically exploited server-based vulnerabilities
and didn't take advantage of a browser based vulnerability like this,"  
he said.

Foundstone discovered the vulnerability in August and disclosed the
information to Microsoft at that time, McClure said.

The vulnerability affects MDAC versions 2.1, 2.5 and 2.6, according to
Microsoft. MDAC is installed and implemented by default in Windows
2000, and within the Windows NT 4.0 option pack.

Machines running Internet Explorer versions 5.01, 5.5 and 6.0 are also
affected by the new vulnerability, Microsoft said.

Earlier versions of either MDAC or Internet Explorer that are no
longer supported may also be vulnerable, the software maker said.

Customers who are potentially affected are advised to review the
appropriate security bulletin, MS02-065, on Microsoft's Web site. The
bulletin is here.

They should then download and install the software patch issued by
Microsoft, which is here.



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