Multiple vulnerabilities have been identified in Internet Explorer, which in combination can be exploited to compromise a user's system.

1) A redirection feature using the "mhtml:" URI handler can be exploited to bypass a security check in Internet Explorer, which normally blocks web pages in the "Internet" zone from parsing local files.

2) The above redirection feature can also be exploited to download and execute a malicious file on a user's system. Successful exploitation requires that script code can be executed in the "MyComputer" zone.

3) A cross-site scripting vulnerability can be exploited to execute script code in the security zone associated with another web page if it contains a subframe. This may potentially allow execution of script code in the "MyComputer" zone.

4) A variant of a fixed vulnerability can still be exploited to hijack a user's clicks and perform certain actions without the user's knowledge.

For more information:
SA9711

5) An error in the download functionality can be exploited to disclose a user's cache directory by supplying a "HTM" file extension and an invalid value in the "Content-Type:" header field. This issue does not affect all versions and may have been fixed by the latest patch for Internet Explorer.

The vulnerabilities have been reported in Internet Explorer 6.0. However, other versions may also be affected and have been added due to the criticality of these issues.

PoC exploits (Proof of Concept) are available.

Solution
Apply patches manually or via WindowsUpdate.
Further details available to Secunia VIM customers

Provided and/or discovered by
Liu Die Yu

Changelog
Further details available to Secunia VIM customers

Original Advisory
Microsoft Security Bulletin MS04-004:
http://www.microsoft.com/technet/security/bulletin/MS04-004.asp

http://www.safecenter.net/UMBRELLAWEBV4/DirSvc/security/originality/microsoft_ie/index.html

http://www.safecenter.net/UMBRELLAWEBV4/1stCleanRc
http://www.safecenter.net/UMBRELLAWEBV4/MhtRedirParsesLocalFile
http://www.safecenter.net/UMBRELLAWEBV4/MhtRedirLaunchInetExe
http://www.safecenter.net/UMBRELLAWEBV4/BackToFramedJpu
http://www.safecenter.net/UMBRELLAWEBV4/HijackClickV2
http://www.safecenter.net/UMBRELLAWEBV4/threadid10008
http://www.safecenter.net/UMBRELLAWEBV4/LocalZoneInCache
http://www.safecenter.net/UMBRELLAWEBV4/execdror6

Other references
Further details available to Secunia VIM customers

Deep Links
Links available to Secunia VIM customers