Secunia Research: Internet Explorer File Download Handling Memory Corruption

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                     Secunia Research 09/10/2007

    - Internet Explorer File Download Handling Memory Corruption -

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Table of Contents

Affected Software....................................................1
Severity.............................................................2
Description of Vulnerability.........................................3
Solution.............................................................4
Time Table...........................................................5
Credits..............................................................6
References...........................................................7
About Secunia........................................................8
Verification.........................................................9

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1) Affected Software 

* Internet Explorer 5.01
* Internet Explorer 6
* Internet Explorer 7

NOTE: Other versions may also be affected.

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2) Severity 

Rating: Highly critical
Impact: System compromise
Where:  Remote

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3) Description of Vulnerability

Secunia Research has discovered a vulnerability in Internet Explorer,
which can be exploited by malicious people to compromise a user's
system.

The vulnerability is caused due to an error in the file download queue
handling when processing multiple concurrent attempts to start a file
download. This can be exploited via a specially crafted web page to
corrupt memory in a way that results in use of an already freed 
object.

Successful exploitation allows execution of arbitrary code.

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4) Solution 

Apply patches (see Microsoft security bulletin for details).

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5) Time Table 

04/01/2007 - Vendor notified.
04/01/2007 - Vendor response.
09/10/2007 - Public disclosure.

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6) Credits 

Discovered by Carsten Eiram, Secunia Research.

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7) References

The Common Vulnerabilities and Exposures (CVE) project has assigned 
CVE-2007-3893 for the vulnerability.

MS07-057 (KB939653):
http://www.microsoft.com/technet/security/Bulletin/MS07-057.mspx

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8) About Secunia

Secunia offers vulnerability management solutions to corporate
customers with verified and reliable vulnerability intelligence
relevant to their specific system configuration:

http://corporate.secunia.com/

Secunia also provides a publicly accessible and comprehensive advisory
database as a service to the security community and private 
individuals, who are interested in or concerned about IT-security.

http://secunia.com/

Secunia believes that it is important to support the community and to
do active vulnerability research in order to aid improving the 
security and reliability of software in general:

http://corporate.secunia.com/secunia_research/33/

Secunia regularly hires new skilled team members. Check the URL below
to see currently vacant positions:

http://secunia.com/secunia_vacancies/

Secunia offers a FREE mailing list called Secunia Security Advisories:

http://secunia.com/secunia_security_advisories/ 

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9) Verification 

Please verify this advisory by visiting the Secunia website:
http://secunia.com/secunia_research/2007-31/

Complete list of vulnerability reports published by Secunia Research:
http://secunia.com/secunia_research/

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