Vendor : phpBB Group

URL : http://www.phpbb.com

Version : phpBB 2.0.6d && Earlier

Risk : Cross Site Scripting

Description:

phpBB is a high powered, fully scalable, and highly customisable open-source

bulletin board package. phpBB has a user-friendly interface, simple and straight

forward administration panel, and helpful FAQ. Based on the powerful PHP server

language and your choice of MySQL, MS-SQL, PostgreSQL or Access/ODBC database

servers, phpBB is the ideal free community solution for all web sites.

Problem:

phpBB is a great forum system used by many millions of people. It is one of

the more secure of the forum systems, but has a few issues still present; both

of which allow for XSS (Cross Site Scripting). This problem presents itself in

two different places.One of these places is viewtopic.php and the other is

viewforum.php Below are examples along with a brief explanation on how to

replicate this issue.

viewforum.php?f=[FNUM]&topicdays=[DNUM][XSS]

FNUM is a valid forum number. DNUM is the number of days to check. If you get no

results with the number 1 for example try the number 99 and so forth and so on.

XSS is whatever code is injected.

viewtopic.php?t=[TNUM]&postdays=[DNUM][XSS]

This is nearly the same issue as above, it just happens to be present in multiple

files. The only difference is TNUM is a valid topic id number. Remember, the query

must display results in order for the XSS to take place. Additionally the offset

(start) variable may be used to get results, but in most cases is unnecessary.

Examples are below though.

Examples:

viewforum.php?f=1&topicdays=99"><script>alert(document.cookie)<
/script>&start=30

viewtopic.php?t=10&postdays=99"><script>alert(document.cookie)<
/script>&start=20

Solution:

I have released a fix for this vulnerability. It requires a valid integer for the

affected variables, and thus eliminates this vulnerability from taking place. You

can find the fix by following the link below.

http://www.gulftech.org/vuln/phpBB2.0.6dfix.rar

Alternatively you can do it yourself by following the instructions listed below.

-----[ OPEN ]-----------------------------------

viewforum.php

-----[ FIND ]-----------------------------------

if ( !empty($HTTP_POST_VARS['topicdays']) || !empty($HTTP_GET_VARS['topicdays']) )

{

$topic_days = ( !empty($HTTP_POST_VARS['topicdays']) ) ? $HTTP_POST_VARS['topicdays'] : $HTTP_GET_VARS['topicdays'];

$min_topic_time = time() - ($topic_days * 86400);

-----[ REPLACE WITH ]---------------------------

if ( !empty($HTTP_POST_VARS['topicdays']) || !empty($HTTP_GET_VARS['topicdays']) )

{

///////////////////////////////////////////////////////////////////

// Lets Do Away With These Problems By Requiring A Valid Integer //

// Fix By JeiAr // http://www.gulftech.org // Friday 03 12, 2004 //

///////////////////////////////////////////////////////////////////

$topic_days = ( !empty($HTTP_POST_VARS['topicdays']) ) ? intval($HTTP_POST_VARS['topicdays']) : intval($HTTP_GET_VARS['topicdays']);

$min_topic_time = time() - ($topic_days * 86400);

-----[ OPEN ]-----------------------------------

viewtopic.php

-----[ FIND ]-----------------------------------

if( !empty($HTTP_POST_VARS['postdays']) || !empty($HTTP_GET_VARS['postdays']) )

{

$post_days = ( !empty($HTTP_POST_VARS['postdays']) ) ? $HTTP_POST_VARS['postdays'] : $HTTP_GET_VARS['postdays'];

$min_post_time = time() - (intval($post_days) * 86400);

-----[ REPLACE WITH ]---------------------------

if( !empty($HTTP_POST_VARS['postdays']) || !empty($HTTP_GET_VARS['postdays']) )

{

///////////////////////////////////////////////////////////////////

// Lets Do Away With These Problems By Requiring A Valid Integer //

// Fix By JeiAr // http://www.gulftech.org // Friday 03 12, 2004 //

///////////////////////////////////////////////////////////////////

$post_days = ( !empty($HTTP_POST_VARS['postdays']) ) ? intval($HTTP_POST_VARS['postdays']) : intval($HTTP_GET_VARS['postdays']);

$min_post_time = time() - (intval($post_days) * 86400);

phpBB development team will be releasing an official fix soon. Please check their

website, or the SourceForge projects page of phpBB for any updates. The SourceForge

projects page for phpBB can be located @ http://sourceforge.net/projects/phpbb The

fix supplied here should suffice though. If you feel this is incorrect please contact

me with details of any problems you experience. And a big thanks to Meik Sievertsen

and the rest of the phpBB team for addressing these issues in a very prompt and

professional manner. Original advisory located @ http://www.gulftech.org/03122004.php

Credits:

Credits go to JeiAr of the GulfTech Security Research Team.

http://www.gulftech.org

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