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National Cyber Alert System
Technical Cyber Security Alert TA04-293A
Multiple Vulnerabilities in Microsoft Internet Explorer
Original release date: October 19, 2004
Last revised: --
Source: US-CERT
Systems Affected
Microsoft Windows systems running
* Internet Explorer versions 5.01 and later; previous,
unsupported versions of Internet Explorer may also be affected
* Programs that use the WebBrowser ActiveX control (WebOC) or
MSHTML rendering engine
Overview
Microsoft Internet Explorer (IE) contains multiple vulnerabilities,
the most severe of which could allow a remote attacker to execute
arbitrary code with the privileges of the user running IE.
I. Description
Microsoft Security Bulletin MS04-038 describes a number of IE
vulnerabilities, including buffer overflows, cross-domain
scripting, spoofing, and "drag and drop." Further details are
available in the following vulnerability notes:
* VU#291304 - Microsoft Internet Explorer contains a buffer overflow
in CSS parsing
A buffer overflow vulnerability exists in the way that IE
processes Cascading Style Sheets (CSS). This could allow an
attacker to execute arbitrary code or cause a denial of service.
(CAN-2004-0842)
* VU#637760 - Microsoft Internet Explorer Install Engine contains a
buffer overflow vulnerability
The IE Active Setup Install Engine (inseng.dll), which is used to
decompress ActiveX controls stored in CAB files, contains a buffer
overflow vulnerability. This could allow an attacker to execute
arbitrary code. (CAN-2004-0216)
* VU#207264 - Microsoft Internet Explorer does not properly handle
function redirection (Similar Method Name Redirection Cross Domain
Vulnerability)
IE does not properly validate redirected functions. The impact is
similar to that of a cross-site scripting vulnerability, allowing
an attacker to access data and execute script in other domains,
including the Local Machine Zone. (CAN-2004-0727)
* VU#526089 - Microsoft Internet Explorer treats arbitrary files as
images for drag and drop operations (Drag and Drop Vulnerability)
IE treats arbitrary files as images during "drag and drop" mouse
operations. This could allow an attacker to trick a user into
copying a file to a location where it could be executed, such as
the user's Startup folder. (CAN-2004-0839)
* VU#413886 - Microsoft Internet Explorer allows mouse events to
manipulate window objects and perform "drag and drop" operations
(Script in Image Tag File Download Vulnerability, HijackClick 3)
IE dynamic HTML (DHTML) mouse events can manipulate windows to
copy objects from one domain to another, including the Local
Machine Zone. This could allow an attacker to write an arbitrary
file to the local file system in a location where it could be
executed, such as the user's Startup folder. (CAN-2004-0841)
In addition, MS04-038 describes two address bar spoofing
vulnerabilities (VU#625616, VU#431576) that could allow an attacker
to deceive a user about the location of a web site; a vulnerability
involving cached HTTPS files (VU#795720) that could allow an
attacker to read from or inject data into an HTTPS web site; and a
vulnerability in which IE6 on Windows XP ignores the "Drag and drop
and copy and paste files" setting (VU#630720).
Any program that uses the WebBrowser ActiveX control (WebOC) or
MSHTML rendering engine could be affected by these vulnerabilities.
II. Impact
The impacts of these vulnerabilities vary, but an attacker may be
able to execute arbitrary code with the privileges of the user
running IE. An attacker could also exploit these vulnerabilities
to perform social engineering attacks such as spoofing or phishing
attacks. In most cases, an attacker would need to convince a user
to view an HTML document (web page, HTML email message) with IE or
another program that uses the WebBrowser ActiveX control or MSHTML
rendering engine.
In some cases, an attacker could combine two or more
vulnerabilities to write an arbitrary file to the local file system
in a sensitive location, such as the user's Startup folder. US-CERT
has monitored reports of attacks against some of these
vulnerabilities.
III. Solution
Apply a patch
Apply the appropriate patch as specified by Microsoft Security
Bulletin MS04-038.
Disable Active scripting and ActiveX controls
To protect from attacks against several of these vulnerabilities,
disable Active scripting and ActiveX controls in any zone used to
render untrusted HTML content (typically the Internet Zone and
Restricted Sites Zone). Instructions for disabling Active scripting in
the Internet Zone can be found in the Malicious Web Scripts FAQ.
Upgrade to Windows XP Service Pack 2
Service Pack 2 for Windows XP contains security improvements for IE
that reduce the impact of some of these vulnerabilities.
Appendix A. References
* Vulnerability Note VU#291304 -
<http://www.kb.cert.org/vuls/id/291304>
* Vulnerability Note VU#637760 -
<http://www.kb.cert.org/vuls/id/637760>
* Vulnerability Note VU#207264 -
<http://www.kb.cert.org/vuls/id/207264>
* Vulnerability Note VU#526089 -
<http://www.kb.cert.org/vuls/id/526089>
* Vulnerability Note VU#413886 -
<http://www.kb.cert.org/vuls/id/413886>
* Vulnerability Note VU#625616 -
<http://www.kb.cert.org/vuls/id/625616>
* Vulnerability Note VU#431576 -
<http://www.kb.cert.org/vuls/id/431576>
* Vulnerability Note VU#795720 -
<http://www.kb.cert.org/vuls/id/795720>
* Vulnerability Note VU#630720 -
<http://www.kb.cert.org/vuls/id/630720>
* Vulnerability Note VU#673134 -
<http://www.kb.cert.org/vuls/id/673134>
* Malicious Web Scripts FAQ -
<http://www.cert.org/tech_tips/malicious_code_FAQ.html>
* Microsoft Security Bulletin MS04-038 -
<http://www.microsoft.com/technet/security/bulletin/ms04-038.mspx>
_________________________________________________________________
Information used in this document came from Microsoft Security
Bulletin MS04-038. Microsoft credits Greg Jones, Peter Winter-Smith,
Mitja Kolsek, and John Heasman for reporting several vulnerabilities.
Will Dormann reported the IE6 Windows XP drag and drop setting
vulnerability.
_________________________________________________________________
Feedback can be directed to the authors: Art Manion and Will Dormann.
_________________________________________________________________
This document is available from:
<http://www.us-cert.gov/cas/techalerts/TA04-293A.html>
_________________________________________________________________
Copyright 2004 Carnegie Mellon University.
Terms of use:
<http://www.us-cert.gov/legal.html>
_________________________________________________________________
Revision History
October 19, 2004: Initial release
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