Security Advisory -//- phpBB 2.0.15 PHP-code injection bug Program: phpBB 2.0.15 and older versions Homepage: http://www.phpbb.com Risk: Very High Date: June 28 2005 Title: PHP-code injection bug Type: partial disclosure Author: Ron van Daal :. Vendor notified: June 23 2005 Background: phpBB is a high powered, fully scalable, and highly customizable Open Source bulletin board package. Based on the PHP server language and supporting a variety of backend database servers. Description: Due to a bug in the phpBB highlighting code it's possible to inject PHP-code into the running script. E.g. It's possible to run system commands if the PHP interpreter allows system() and simular functions. This is actually based on an old bug which was improperly fixed in phpBB 2.0.11. Technical: The highlighting code uses the preg_replace() function on line 1110 in viewtopic.php. It uses the special modifier "e" which causes PHP to evaluate the replacement string as PHP code. Below is a PHP code example of what actually happens: $string1="phpinfo()"; $string2=preg_replace('//e',$string1,''); ?> This causes PHP to execute the phpinfo() function. Usage of the preg_replace special modifier "e" should be avoided if possible. Proof of concept: Sorry, partial disclosure advisory. Solution: Upgrade to phpBB version 2.0.16 or edit viewtopic.php on line #1110: Change this: str_replace('\\', '\\\\', $highlight_match) Into this: str_replace('\\', '\\\\', addslashes($highlight_match)) Credits: Synto(nix) && Doqnach @Umbranet #unixtalk
-- Theo de Raadt: "BSD guys are a lot like Linux guys, except they have kissed girls" Methinks: "FreeBSD guys are a lot like OpenBSD guys, except they have fscked girls"