Unicode Buffer Overflow in WinFtp Server 1.6.8

["Donato Ferrante" <fdonato () autistici org>]

                           Donato Ferrante


Application:  WinFtp Server
              http://www.wftpserver.com

Version:      1.6.8

Bug:          Unicode Buffer Overflow

Date:         17-Aug-2005

Author:       Donato Ferrante
              e-mail: fdonato () autistici org
              web:    www.autistici.org/fdonato



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1. Description
2. The bug
3. The code
4. The fix



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1. Description:
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Vendor's Description:

"WinFTP Server is a multithreaded FTP server for Windows 98/NT/XP."



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2. The bug:
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The bug is located in the "Log To Screen" feature, this feature
allows the program to show server's log on screen.
By default the program has this function (called Log-SCR) enabled.
So a malicious user can trigger an unicode buffer overflow.



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3. The code:
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To test the vulnerability send a request to the FTP server like:

aaa [1024 of a] aaa

and then scroll down the log screen, so the server will crash.



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4. The fix:
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Vendor has been contacted.
Bug will be fixed in the next release.



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