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                     Secunia Research 18/02/2005

        - Yahoo! Messenger File Transfer Filename Spoofing -

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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

Yahoo! Messenger 6.0.0.1750

Other versions may also be affected.

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2) Severity

Rating: Less critical
Impact: Spoofing
Where:  From remote

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3) Description of Vulnerability

Secunia Research has discovered a vulnerability in Yahoo! Messenger, 
which can be exploited by malicious people to trick users into 
executing malicious files.

The problem is that files with long filenames are not displayed 
correctly in the file transfer dialogs. This can be exploited to 
trick users into accepting and potentially executing malicious files.

Details:
Yahoo! Messenger wraps overly long filenames and shows only the first 
line of the filename in the file transfer dialogs. The file extension 
can thus be spoofed for a filename containing a whitespace and two 
file extensions.

Successful exploitation requires that the option 
"Hide extension for known file types" is enabled in Windows 
(default setting).

The vulnerability has been confirmed in version 6.0.0.1750. Other 
versions may also be affected.

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4) Solution

Update to version 6.0.0.1921.
http://messenger.yahoo.com/

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5) Time Table

04/01/2005 - Vulnerability discovered.
10/01/2005 - Vendor notified.
19/01/2005 - Vendor confirms the vulnerability.
17/02/2005 - Vendor issued fixed version.
18/02/2005 - Public disclosure.

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6) Credits

Discovered by Andreas Sandblad, Secunia Research.

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7) References

The Common Vulnerabilities and Exposures (CVE) project has assigned 
candidate number CAN-2005-0243 for the vulnerability.

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8) About Secunia

Secunia collects, validates, assesses, and writes advisories regarding
all the latest software vulnerabilities disclosed to the public. These
advisories are gathered in a publicly available database at the
Secunia web site:

http://secunia.com/

Secunia offers services to our customers enabling them to receive all
relevant vulnerability information to their specific system
configuration.

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 web site:
http://secunia.com/secunia_research/2005-2/advisory/

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