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RE: YaBB/YaBBse Cross Site Scripting Vulnerability



Hello,
this hole was discovered on 29/02/04 and published in french here :
http://www.phpsecure.info/v2/tutos/frog/YaBBSE-XSSPermanent.txt
We were waiting an official security fix by the YabbSE team (since 1 month) to published the hole on some mailing-lists but they always didn't make anything.
Another security hole is :

[glow=red,2);background:url(javascript:[SCRIPT],300]text[/glow]

The new YabbSE-Team's project (SMF 1.0b http://www.simplemachines.org ) seems to be bugged too.

To fix these holes, you just have to replaced the lines :

--------------------------------------------------------------------------
                        '/\[glow=(.+?),(.+?),(.+?)\](.+?)\[\/glow\]/eis',
                        '/\[shadow=(.+?),(.+?)\](.+?)\[\/shadow\]/eis',
--------------------------------------------------------------------------

by :

-----------------------------------------------------------------------------------
                        
'/\[glow=([[:alpha:]]+?),(.+?),(.+?)\](.+?)\[\/glow\]/eis',
                        
'/\[shadow=([[:alpha:]]+?),(.+?)\](.+?)\[\/shadow\]/eis',
-----------------------------------------------------------------------------------

and the line :

-----------------------------------------------------------------------------------------------------------------------------
"'<table style=\"border 0px;\"><tr><td style=\"filter:Glow(color=\\1, strength=' . ('\\2' < 255 ? '\\2' : '255') . ');\">' . \"\\4\" . '</td></tr></table>'",
-----------------------------------------------------------------------------------------------------------------------------

by :

-----------------------------------------------------------------------------------------------------------------------------
"'<table style=\"border 0px;\"><tr><td style=\"filter:Glow(color=\\1, strength=' . intval( ('\\2' < 255 ? '\\2' : '255') ) . ');\">' . \"\\4\" . '</td></tr></table>'",
-----------------------------------------------------------------------------------------------------------------------------


in the file Sources/Subs.php.



A fix can be found on http://www.phpsecure.info



Sorry for my poor english,
Germain Randaxhe aka frog-m@n

http://www.phpsecure.info
http://www.security-corporation.com





From: Cheng Peng Su <apple_soup@xxxxxxx>
To: bugtraq@xxxxxxxxxxxxxxxxx
Subject: YaBB/YaBBse Cross Site Scripting Vulnerability
Date: 14 Mar 2004 07:52:07 -0000




#####################################################################

 Advisory Name : YaBB/YaBBse Cross Site Scripting Vulnerability
  Release Date : Mar 14,2004
   Application : YaBB/YaBBse
       Test On : YaBB 1 Gold(SP1.3)
                 YaBB SE 1.5.1 Final
    Vendor URL : http://www.yabbforum.com/
                 http://www.yabbse.org/
      Discover : Cheng Peng Su(apple_soup_at_msn.com)

#####################################################################

  Proof of conecpt:
      The problem is in [glow] and [shadow] tag,yabb doesn't filter
   the charactor in this tag,attack needn't visitor to click any
   links,just when the vistor read the thread,XSS code will be
   executed.

  Exploit:
   [glow=red);background:url(javascript:alert(document.cookie));filte
   r:glow(color=red,2,300]Big Exploit[/glow]
   [shadow=red);background:url(javascript:alert(document.cookie));fil
   ter:shadow(color=red,left,300]Big Exploit[/shadow]

  Contact:
   Cheng Peng Su
   Class 1,Senior 2,High school attached to Wuhan University
   Wuhan,Hubei,China(430072)
   apple_soup_at_msn.com





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