phpBB Input Validation Flaw in 'viewtopic.php' 'postorder' Variable Lets Remote Users Conduct Cross-Site Scripting Attacks
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SecurityTracker Alert ID: 1009256
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CVE Reference: CAN-2004-0339
(Links to External Site)
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Updated: Mar 23 2004
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Original Entry Date: Feb 28 2004
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Impact: Disclosure of authentication information, Disclosure of user information, Execution of arbitrary code via network, Modification of user information
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Exploit Included: Yes
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Version(s): 2.0.6c
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Description: An input validation vulnerability was reported in phpBB in 'viewtopic.php'. A remote user can conduct cross-site scripting attacks.
Cheng Peng Su reported that the script does not validate user-supplied input in the 'postorder' variable. A remote user can create
a specially crafted URL that, when loaded by a target user, will cause arbitrary scripting code to be executed by the target user's
browser. The code will originate from the site running the phpBB software and will run in the security context of that site. As
a result, the code will be able to access the target user's cookies (including authentication cookies), if any, associated with
the site, access data recently submitted by the target user via web form to the site, or take actions on the site acting as the
target user.
A demonstration exploit URL is provided:
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%7
5%6D%65%6E%74%2E%63%6F%6F%6B%69%65%
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Impact: A remote user can access the target user's cookies (including authentication cookies), if any, associated with the site running the
phpBB software, access data recently submitted by the target user via web form to the site, or take actions on the site acting as
the target user.
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Solution: No solution was available at the time of this entry.
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Vendor URL: www.phpbb.com/ (Links to External Site)
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Cause: Input validation error
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Underlying OS: Linux (Any), UNIX (Any), Windows (Any)
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Reported By: Cheng Peng Su <apple_soup@msn.com>
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: 28 Feb 2004 15:09:02 -0000
From: Cheng Peng Su <apple_soup@msn.com>
Subject: New phpBB ViewTopic.php Cross Site Scripting Vulnerability
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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)
################################################
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&start=0&postday
s=0&postorder=asc&highlight=">[Topic Title]</a>.
phpBB doesn't filter out illegal characters from 'postorder',so we can inject HTML code after 'post
order='.
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%6
F%6B%69%65%29%3C%2F%73%63%72%69%70%74%3E%3C')
== '"><script>alert(document.cookie)</script><'
Contact:
Cheng Peng Su
apple_soup_at_msn.com
Class 1,Senior 2,High school attached to Wuhan University
Wuhan,Hubei,China
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