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IPB v2.x up to 3.0.4 XSS vulnerability



[+] Invision Power Board XSS vulnerability

	Software : Invision Power Board (IPB)
	Affected : IPB v2.x up to v3.0.4 (prior versions might be vulnerable as well)
	Remote   : Yes
	Required : Internet Explorer +5.0
	Vendor   : http://www.invisionpower.com/
	Download : Commercially available
	Author   : Xacker
	Contact  : N/A
	Blog     : http://xacker.wordpress.com
	Website  : N/A


[+] Technical details

	IP.Board is prone to XSS attacks through maliciously crafted *.txt
files attachments. An attacker has to convince a user to view the
malicious file in order to run the evil code.

	The only browser found affected is Internet Explorer +5.0, other
browsers (FF/Chrome/Opera..) seems to handle the issue correctly (or
simply blindly?)

	IP.Board v2.x set the MIME-type of *.txt files to
(application/x-dirview). If the *.txt file contains JavaScript/HTML it
will simply be parsed on IE +5.

	IP.Board v3.0.4 (and prior) seems to check the content of the files
before permitting them, tags like "<body> , <script> , etc.." are
flagged *dangerous* any file containing any of them simply fail to be
uploaded. The filter itself is weak, to escape it I provide a
proof-of-concept code below.


[+] Exploit

	--------------------------------->8---------------------------------
	<span onmouseover="javascript:alert('XSS');function
fakeLoginPage(){...}">move your mouse pointer here</span>
	---------------------------------8<---------------------------------

	fakeLoginPage() function can be used to rewrite the whole page,
faking a login page through an embedded iframe.


[+] Fix

	Simply change MIME-type of *.txt files (and any other similar
formats) to (text/plain).


[+] Note

	IP.Board technical staff has been notified of the issue and a fix has
been released couple of days ago:
	http://community.invisionpower.com/topic/300051-invision-power-board-305-released/