M-126: Microsoft VM JDBC Classes Vulnerabilities

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Microsoft Security Bulletin MS02-052 

Flaw in Microsoft VM JDBC Classes Could Allow Code Execution (Q329077)
Originally posted: September 18, 2002


Summary

Who should read this bulletin: All customers using Microsoft® Windows®. 

Impact of vulnerability: Three vulnerabilities, the most serious of which could enable 
an attacker to gain complete control over a user’s system. 

Maximum Severity Rating: Critical 

Recommendation: Customers should apply the patch immediately. 

Affected Software: 
Versions of the Microsoft virtual machine (Microsoft VM) are identified by build 
numbers, which can be determined using the JVIEW tool as discussed in the FAQ. All 
builds of the Microsoft VM up to and including build 5.0.3805 are affected by these 
vulnerabilities. 



Technical details

Technical description: 

The Microsoft VM is a virtual machine for the Win32® operating environment. The 
Microsoft VM shipped in most versions of Windows (a complete list is available in the 
FAQ), as well as in most versions of Internet Explorer. It also was available for some 
time as a separate download. A new patch for the Microsoft VM is available, which 
eliminates three security vulnerabilities. The attack vectors for all of them would 
likely be the same. An attacker would likely create a web page that, when opened, 
exploits the desired vulnerability, and either host it on a web page or send it to a 
user as an HTML mail. 

The first vulnerability involves the Java Database Connectivity (JDBC) classes, which 
provide features that allow Java applications to connect to and use data from a wide 
variety of data sources, ranging from flat files to SQL Server databases. The 
vulnerability results because of a flaw in the way the classes vet a request to load 
and execute a DLL on the user’s system. Although the classes do perform checks that 
are designed to ensure that only authorized applets can levy such a request, it’s 
possible to spoof this check by malforming the request in a particular way, thereby 
enabling an attacker to load and execute any DLL on the user’s system. 

The second vulnerability also involves the JDBC classes, and occurs because certain 
functions in the classes don’t correctly validate handles that are provided as input. 
One straightforward use of this flaw would involve supplying invalid data in lieu of 
an actual handle when calling such a function. Microsoft has confirmed that this 
scenario would cause Internet Explorer to fail. In addition, there is at least a 
theoretical possibility that the flaw also could enable an attacker to provide data 
that would have the effect of running code in the security context of the user. 

The third vulnerability involves a class that provides support for the use of XML by 
Java applications. This class exposes a number of methods; some of these are suitable 
for use by any applet, while others are only suitable for use by trusted ones. 
However, the class does not differentiate correctly between these cases, and instead 
makes all of the methods available to all applets. Among the functions that could be 
misused through this vulnerability are ones that would enable an applet to take 
virtually any desired action on the user’s system. 


Mitigating factors: 

In order to exploit any of these vulnerabilities via the web-based attack vector, the 
attacker would need to entice a user into visiting a web site that the attacker 
controlled. The vulnerabilities themselves provide no way to force a user to a web 
site. 

Java applets are disabled within the Restricted Sites Zone. As a result, any mail 
client that opened HTML mail within the Restricted Sites Zone, such as Outlook 2002, 
Outlook Express 6, or Outlook 98 or 2000 when used in conjunction with the Outlook 
Email Security Update, would not be at risk from the mail-based attack vector. 

The vulnerability would gain only the privileges of the user, so customers who operate 
with less than administrative privileges would be at less risk from the vulnerability. 

Corporate IT administrators could limit the risk posed to their users by using 
application filters at the firewall to inspect and block mobile code. 


Severity Rating:              Internet Servers    Intranet Servers   Client Systems 
DLL execution via JDBC classes    Moderate            Moderate         Critical 
Handle validation flaw            Low                 Low              Low 
Inappropriate methods exposed     Moderate            Moderate         Critical 
  in XML support classes

The above assessment is based on the types of systems affected by the vulnerability, 
their typical deployment patterns, and the effect that exploiting the vulnerability 
would have on them. 

Vulnerability identifier: 

DLL execution via JDBC classes: CVE-CAN-2002-0866 

Handle validation flaw: CVE-CAN-2002-0867 

Inappropriate methods exposed in XML support classes: CVE-CAN-2002-0865 

Tested Versions:
Microsoft tested VM builds 5.0.3167 and later to assess whether they are affected by 
these vulnerabilities. Previous versions are no longer supported, and may or may not 
be affected by these vulnerabilities.





Patch availability

Download location for this patch: 
  http://Windowsupdate.microsoft.com



Additional information about this patch

Installation platforms: 
This patch to the Microsoft VM can be installed on systems that are already running 
the 5.0.3805 version of the Microsoft VM. 

Inclusion in future service packs:
The fix for this issue will be included in all future Microsoft VM builds. 

Reboot needed: Yes 

Patch can be uninstalled: No 

Superseded patches: None. 

Verifying patch installation: The Knowledge Base article Q329077 provides information 
to verify that you've installed the patch.

Note: Regardless of the version number viewed from Jview, the registry key described 
in the above article should be the determining factor for proper installation of this 
patch. 

Caveats:
None 

Localization:
This patch will install all language versions. 

Obtaining other security patches: 
Patches for other security issues are available from the following locations: 

Security patches are available from the Microsoft Download Center, and can be most 
easily found by doing a keyword search for "security_patch". 

Patches for consumer platforms are available from the WindowsUpdate web site


 
Other information: 

Support: 

Microsoft Knowledge Base article Q329077 discusses this issue and will be available 
approximately 24 hours after the release of this bulletin. Knowledge Base articles can 
be found on the Microsoft Online Support web site. 

Technical support is available from Microsoft Product Support Services. There is no 
charge for support calls associated with security patches. 

Security Resources: The Microsoft TechNet Security Web Site provides additional 
information about security in Microsoft products. 

Disclaimer: 
The information provided in the Microsoft Knowledge Base is provided "as is" without 
warranty of any kind. Microsoft disclaims all warranties, either express or implied, 
including the warranties of merchantability and fitness for a particular purpose. In 
no event shall Microsoft Corporation or its suppliers be liable for any damages 
whatsoever including direct, indirect, incidental, consequential, loss of business 
profits or special damages, even if Microsoft Corporation or its suppliers have been 
advised of the possibility of such damages. Some states do not allow the exclusion or 
limitation of liability for consequential or incidental damages so the foregoing 
limitation may not apply. 


Revisions: 


V1.0 (September 18, 2002): Bulletin Created. 

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