phpBB: Remote command execution

Background

phpBB is an Open Source bulletin board package.

Description

phpBB contains a vulnerability in the highlighting code and several vulnerabilities in the username handling code.

Impact

An attacker can exploit the highlighting vulnerability to access the PHP exec() function without restriction, allowing them to run arbitrary commands with the rights of the web server user (for example the apache user). Furthermore, the username handling vulnerability might be abused to execute SQL statements on the phpBB database.

Workaround

There is a one-line patch which will remediate the remote execution vulnerability.

Locate the following block of code in viewtopic.php:

// // Was a highlight request part of the URI? // $highlight_match = $highlight = ''; if (isset($HTTP_GET_VARS['highlight'])) { // Split words and phrases $words = explode(' ', trim(htmlspecialchars(urldecode($HTTP_GET_VARS['highlight'])))); for($i = 0; $i < sizeof($words); $i++) {

Replace with the following:

// // Was a highlight request part of the URI? // $highlight_match = $highlight = ''; if (isset($HTTP_GET_VARS['highlight'])) { // Split words and phrases $words = explode(' ', trim(htmlspecialchars($HTTP_GET_VARS['highlight']))); for($i = 0; $i < sizeof($words); $i++) {

Resolution

All phpBB users should upgrade to the latest version to fix all known vulnerabilities:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=www-apps/phpbb-2.0.11"