Microsoft Security Bulletin (MS00-059)
Patch Available for "Java VM Applet" Vulnerability
Originally posted: August 21, 2000
Microsoft has released a patch that eliminates a security
vulnerability in the Microsoft(r) virtual machine (Microsoft VM). If
a malicious web site operator were able to coax a user into visiting
his site, the vulnerability could allow him to masquerade as the
user, visit other sites using his identity, and relay the information
back to his site.
Frequently asked questions regarding this vulnerability and the patch
can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-059.asp
The Microsoft VM is a virtual machine for the Win32(r) operating
environment. It runs atop Microsoft Windows(r) 95, 98, or Windows
NT(r), or Windows 2000. It ships as part of each operating system,
and also as part of Microsoft Internet Explorer. The version of the
Microsoft VM that ships with Microsoft Internet Explorer 4.x and
Internet Explorer 5.x contains a security vulnerability that could
allow a Java applet to operate outside the bounds set by the sandbox.
By design, an applet should only be able to communicate with the web
site that hosted it. However, this vulnerability would allow an
applet to bypass this restriction. If a user visited a web site
operated by a malicious user, the site could start an applet that
would be able to establish a connection with another web site and
forward any information from the web session to the malicious user's
site.
The session would be established in the guise of the visiting user,
rather than that of the malicious user. Thus, the vulnerability could
be used to access an intranet site located behind a firewall, access
information in the guise of the user, and relay it to the malicious
user. The only prerequisite is that the malicious user would need to
know or guess the name of the intranet site. Although the applet
would be able to make use of the user's credentials to authenticate
to the site, this vulnerability would not provide a
way to compromise them.
Versions of the Microsoft VM are identified by build numbers, which
can be determined using the JVIEW tool, as discussed in the FAQ. The
following builds of the Microsoft VM are affected:
All 2000 series Microsoft VM customers:
Install Microsoft VM build 2446
All 3100 series Microsoft VM customers:
Upgrade to build 3309 and install the 3314 security patch
3200 series Microsoft VM customers should do one of the following:
All 3200 builds:
Upgrade to build 3309 and install the 3314 security patch
Builds 3229-3234:
Install the security patch from Bulletin MS00-011 before
installing
this new 3314 security patch
Build 3240:
Install the 3314 security patch
All 3300 series Microsoft VM customers should install the 3314
security patch
Note Additional security patches are available at the Microsoft
Download Center
Please see the following references for more information related to
this issue.
This is a fully supported patch. Information on contacting Microsoft
Product Support Services is available at
http://support.microsoft.com/support/contact/default.asp.
August 21, 2000: Bulletin Created.
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Last Updated August 21, 2000
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