[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

LFI / RCE vlunerability in Joomla Community Builder Enhenced (CBE) Component

 Hello full-disclosure!

Joomla CBE suffers from a local file inclusion vulnerability. As CBE also offers file uploading functionality that allows to upload files that contain php-code, this can be used to execute arbitary system-commands on the host with the webservers privileges.


Affected versions:
- CBE v1.4.10
- CBE v1.4.9
- CBE v1.4.8
(maybe older versions)

Not affaceted:
- CBE v1.4.11 (current)

Vulnerable code:
in cbe.php a file identified by the param "tabname" is included if the "ajaxdirekt" param is set, without sanatizing the value of "tabname" first:
$ajaxdirekt    = JRequest::getVar('ajaxdirekt', null);
    $tabname = JRequest::getVar('tabname', null);

    if ($ajaxdirekt) {
$tabfile = JPATH_SITE.DS.'components'.DS.'com_cbe'.DS.'enhanced'.DS.$tabname.DS.$tabname.".php";
        if (file_exists($tabfile)) {

Exploitation / poc:
will execute the CREDITS.php

Addional attack-vectors:
CBE offers a file-upload function for uploading user profile images. The uploaded file is not checked for beeing well-formed, it only needs to have the right mime-type and maybe (depends on profile-picture configuration) the right size, so we can embed php-code in the profile-picture. Lets say we have registered an account on the site with the user-id 23, then we can execute the backdoor by requesting:


As we stay in the documents-root, we dont even have to worry about safe-mode directory restrictions, and using GIFs will bypass most of CBE's image pre-processing functions during file upload (except file- and image-size checks).

a) check if the contents of an uploaded file contains a php open-tag ('<?php') (requires that the php-short-open-tag option is disabled) b) Joomla offers several functions for accessing POST and GET params, i guess using getWord() instead of getVar() would be a better choice in this case.

04.10.2010 - vendor informed
07.10.2010 - vendor released fixed version
08.10.2010 - public disclosure

Delf Tonder