Microsoft Security Bulletin MS99-048
Patch Available for "Active Setup Control" Vulnerability
Originally Posted: November 11, 1999
Microsoft has released a patch that eliminates a vulnerability that could allow a malicious user to embed an unsafe executable within an email and disguise it as a safe type of attachment. Through a complicated series of steps, the unsafe executable could be made to execute under certain conditions, if the user opened the attachment.
Frequently asked questions regarding this vulnerability can be found at http://www.microsoft.com/technet/security/bulletin/fq99-048.mspx.
A particular ActiveX control allows cabinet files to be launched and executed. This could allow an HTML mail to contain a malicious cabinet file, disguised as a file of an innocuous type. If a user attempted to open this file, the operation would fail but could, depending on the mail package, leave a copy of the file in a known location. The ActiveX control could then be used via a script embedded in the mail to launch the copy, thereby executing the malicious code.
The vulnerability could only be exploited in cases where a mail reader were used that allowed scripts in HTML mail and stored temporary copies of launched programs in known locations. The patch restricts the ability of the control to launch unsigned cabinet files that have been downloaded from the local machine.
Affected Software Versions
- The affected ActiveX control ships as part of Microsoft Internet Explorer 4 and 5
Vulnerability Identifier: CVE-2000-0329
Note Microsoft produces security patches for Internet Explorer 4.01 SP2 and higher. In the event that this package is applied to Internet Explorer 4.01 SP1, the package states that a fix is not needed. This message is incorrect, as the vulnerability does exist on Internet Explorer 4.01 SP1. If you are using Internet Explorer 4.01 SP1, please upgrade to the latest version of Internet Explorer to resolve this issue.
Please see the following references for more information related to this issue.
- Microsoft Security Bulletin MS99-048: Frequently Asked Questions
- Microsoft Knowledge Base (KB) article 244540, Update Available for "Active Setup Control" Vulnerability
Note It may take 24 hours from the original posting of this bulletin for the KB article to be visible.
- Microsoft Security web site
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft Technical Support is available at http://support.microsoft.com/contactussupport/?ws=support.
Microsoft acknowledges Juan Carlos Garcia Cuartango of Spain for bringing this issue to our attention.
- November 11, 1999: Bulletin Created.
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