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Title: Flaw in Microsoft VM JDBC Classes Could Allow Code
Execution (Q329077)
Released: 18 September 2002
Software: Versions of the Microsoft virtual machine (Microsoft VM)
Impact: Three vulnerabilities, the most serious of which could
enable an attacker to gain complete control over a user's
system.
Max Risk: Critical
Bulletin: MS02-052

Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS02-052.asp.

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Issue:

The Microsoft VM is a virtual machine for the Win32(r) operating
environment. The Microsoft VM shipped as part of most versions of
Windows (a complete list is available in the FAQ), as well as part of
most versions of Internet Explorer. It also was available for some
timeas a separate download. A new patch for the Microsoft VM is
available,which eliminates three security vulnerabilities. The
attack vectors forall 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 enable an attacker to
load and execute any DLL on the user's system.

The second vulnerability also involves the JDBC classes, and results
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
othersare 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.

Maximum Risk Rating:

• Internet systems: Moderate
• Intranet systems: Moderate
• Client systems: Critical

Patch Availability:

• A patch is available to fix this vulnerability. Please read the
  Security Bulletin at
  http://www.microsoft.com/technet/security/bulletin/ms02-052.asp
  for information on obtaining this patch.

Acknowledgment:

• <Customer and URL>

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