CVE-2013-6225: Security Advisory ? Curesec Research Team 1. Introduction Advisory ID: Cure-2013-1007 Advisory URL: https://www.curesec.com/de/veroeffentlichungen /advisories.html Blog URL: https://cureblog.de/2013/11/remote-code-execution-in-livezilla/ Affected Product: LiveZilla version 5.0.1.4 Affected Systems Linux/Windows Fixed in: 5.1.0.0 Fixed Version Link: https://www.livezilla.net/downloads/pubfiles/LiveZilla_5.1.0.0_Full.exe Vendor Contact: support@livezilla.net Vulnerability Type: Remote Code Execution / Local File Inclusion Remote Exploitable: Yes Reported to vendor 18.10.2013 Disclosed to public 15.11.2013 Release mode: Coordinated release CVE: CVE-2013-6225 Credentials: crt@curesec.com 2. Vulnerability Description Livezilla is a online chat system used on websites so customers can be contacted by an employee ask their questions and get delivered what they are looking for. The software itself is used basically in every industry. Looking for possible affected systems google reveals: 1.500.000 results. Inside the file ?mobile/php/translation/index.php? the following code can be found: $langFileLocation = ?.?; $LZLANG = Array();if (isset($_GET['g_language'])) { $language = ($_GET['g_language'] != ?) ? $_GET['g_language'] : ?ein?; require ($langFileLocation . ?/langmobileorig.php?); $LZLANGEN = $LZLANG; if (file_exists($langFileLocation . ?/langmobile? . $language . ?.php?)) { require ($langFileLocation . ?/langmobile? . $language . ?.php?); } The ?g_language? GET parameter is not validated before using it in a php require function call. This allows to include files that are stored on a windows server. It is, in this case, not possible to include files, if the php application is running on a linux server because ?/langmobile?+ the language is not a directory and therefore cannot be traversed. In recent PHP versions null bytes are blocked. This means that in this case only files with the PHP extension can be included. Older PHP versions will allow null bytes in the URL and therefore allow Remote Code Execution attacks involving httpd log files or /proc/pid/environ and other techniques to transform this Local File Inclusion into a full Remote Code Execution on Windows and Linux. On Windows systems with PHP versions installed that allow null bytes in the URL it is possible to turn this local file inclusion vulnerability to a full remote code execution vulnerability. This can be done by traversing directories and accessing the apache log file with having the injected the string that follows using a GET request into the log file. As the screendump shows full code execution in this case executing calc.exe on windows is possible. A working exploit for this vulnerability is found in the Appendix of this documents. The error.log or access.log path has to be known prior to running the exploit. 3. Proof of Concept Codes: Code execution URL sample: $nc <target> 80 GET /index.php?test=<?php system($_GET[cmd]); ?> HTTP/1.1 Host: <target> <return> <return> 4. Solution Download and install latest version: https://www.livezilla.net/downloads/pubfiles/LiveZilla_5.1.0.0_Full.exe 5. Report Timeline 18.10.2013 Informed Vendor about Issue 12.11.2013 Vendor informed about the fixed new version 15.11.2013 Disclosed to public