DoS in NETFile FTP/Web Server

["Donato Ferrante" <fdonato@xxxxxxxxxxxxx>]

                           Donato Ferrante


Application:  Fastream NETFile FTP/Web Server
              http://www.fastream.com/

Version:      6.5.1.980

Bug:          Denial Of Service

Date:         19-Apr-2004

Author:       Donato Ferrante
              e-mail: fdonato@xxxxxxxxxxxxx
              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:
----------------

Vendor's description:

"Secure, multi-threaded FTP/HTTP server combined, featuring automatic
virtual links, U/D ratios, quotas, authentication and extremely fast
directory and file caches. Other features include: User and group
permissions with permissions for all standard FTP and HTTP commands.
Serving from behind NAT/PAT. HTTP file uploading and management.
Free for personal use; professional license is required for commercial
usage."



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2. The bug:
------------

The program is unable to manage nonexistent usernames in the login
procedure. So attacker can deny the ftp service by sending crafted
USER and PASS strings.



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3. The code:
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To test the vulnerability:


1-a. connect to the ftp server and when it asks 
     for the USER, type:   anUsername
     for the PASS, type:   aPassword


1-b. send to the ftp server something like:
     USER anUsername
     PASS aPassword



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4. The fix:
------------

Bug fixed in the version 6.5.1.981.



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