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IAA, Redirector and XSS vulnerabilities in WordPress
From: "MustLive" <mustlive () websecurity com ua>
Date: Sat, 5 May 2012 16:01:53 +0300

Hello list!

I want to warn you about security vulnerabilities in WordPress.

These are Insufficient Anti-automation, Redirector and Cross-Site Scripting 
vulnerabilities.

-------------------------
Affected products:
-------------------------

Vulnerable are WordPress 2.0 - 3.3.1.

----------
Details:
----------

Already from WP 2.0 there are Insufficient Anti-automation, Redirector and 
XSS vulnerabilities in wp-comments-post.php. With IAA I've faced just when 
begun using WP in 2006. If the developers fixed vulnerabilities in previous 
two redirectors in WP 2.3, then these vulnerabilities were not fixed even in 
WP 3.3.1

IAA (WASC-21):

Lack of captcha in comment form allows to conduct automated attacks. The 
developers still haven't put captcha in WP comments form (from the first 
version of engine), which besides IAA attacks, also allowed to conduct 
Redirector and XSS attacks.

By default in WordPress the premoderation is turned on, and also there is 
built-in anti-spam filter. But if 10 years ago the premoderation would be 
enough, then long ago this mechanism couldn't be considered as sufficient 
protection against spam, and anti-spam filter had efficiency less then 1% - 
only few from spam messages he marked as spam. And also these mechanisms 
don't protect against below-mentioned attacks. Also plugin Akismet is 
bundled with WP, which is "captcha-less" protection against spam. But by 
default it's turned off and comparing with captcha it's considered as less 
efficient and also doesn't protect against below-mentioned attacks.

Redirector (URL Redirector Abuse) (WASC-38):

Exploit:

http://websecurity.com.ua/uploads/2012/WordPress%20Redirector.html

XSS (WASC-08):

Exploit:

http://websecurity.com.ua/uploads/2012/WordPress%20XSS.html

XSS attack is possible on different browsers, but it's harder to conduct 
then in case of previous two redirectors (via data URI). At IIS web servers 
the redirect is going via Refresh header, and at other web servers - via 
Location header.

Due to nuances of work of this script (filtering of important symbols and 
adding of anchor), for execution of JS code it's needed to use tricky bypass 
methods. This complexity exists as with javascript URI, as with combo 
variant javascript URI + data URI.

Reliable captcha protects against IAA, Redirector and XSS vulnerabilities.

------------
Timeline:
------------

2012.04.26 - disclosed at my site (http://websecurity.com.ua/5818/).

Best wishes & regards,
MustLive
Administrator of Websecurity web site
http://websecurity.com.ua 


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