Security Advisory - phpBB 2.0.15 PHP-code injection bug

From: ronvdaal (ronvdaal_at_zarathustra.linux666.com)
Date: 06/28/05

  • Next message: Cisco Systems Product Security Incident Response Team: "Cisco Security Advisory: RADIUS Authentication Bypass" 
    Date: Tue, 28 Jun 2005 23:03:22 +0200 (CEST)
To: bugtraq@securityfocus.com

    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

    <EOF> 

    --
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"
  • Next message: Cisco Systems Product Security Incident Response Team: "Cisco Security Advisory: RADIUS Authentication Bypass"

    Relevant Pages