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Re: Vulnerability in CB Captcha for Joomla and Mambo



Dear Susan:

Respectfully, why did you subscribe to Bugtraq? I subscribed to be notified when a vulnerability was found with software that I am using. Just saying.

Regards



On Apr 15, 2010, at 2:11 PM, Susan Bradley <sbradcpa@xxxxxxxxxxx> wrote:

Dear Bugtraq.

I am an admin of a site that has Captcha that spam gets through and the CPU sucks.

Honest question -- are you going to post about every site that has lousy captcha? Would it be faster if us admins that have lousy captcha just outted ourselves first?

MustLive wrote:
Hello Bugtraq!

I want to warn you about security vulnerability in plugin CB Captcha
(plug_cbcaptcha) for component Community Builder (com_comprofiler) for Joomla and Mambo. The posting of this advisory to mailing lists was delayed, because I found that there are two different vulnerable versions of plugin
developed by different authors, so I needed to inform all authors.

-----------------------------
Advisory: Vulnerability in CB Captcha for Joomla and Mambo
-----------------------------
URL: http://websecurity.com.ua/4087/
-----------------------------
Affected products: CB Captcha 1.0.2 and previous versions (developed by
Kotofeich), CB Captcha 2.2 and previous versions (developed by Beat).
-----------------------------
Timeline:
17.03.2010 - found vulnerability.
31.03.2010 - disclosed at my site.
01.04.2010 - informed developer of CB Captcha 1.x. And because I found other version of the plugin by another author, and after checking it later I
informed author of CB Captcha 2.x.
13.04.2010 - additionally informed developers of Community Builder (both
joomlapolis.com and communitybuilder.ru).
-----------------------------
Details:

This is Insufficient Anti-automation vulnerability.

This plugin is based on captcha script CaptchaSecurityImages.php and I
already reported about vulnerabilities in CaptchaSecurityImages
(http://websecurity.com.ua/4043/). And in plugin plug_cbcaptcha were fixed all Insufficient Anti-automation and Denial of Service vulnerabilities from
original script, except one.

Insufficient Anti-automation:

In the plugin it's possible to bypass captcha with using of session reusing with constant captcha bypass method (http://websecurity.com.ua/ 1551/), which was described in project Month of Bugs in Captchas. With using of this
method it's possible to bypass protection by sending the same code of
captcha.

It can be done at all pages where this plugin is used. In CB Captcha 1.x it's using at registration page, lost password form and lost email form. In CB Captcha 2.x, in addition to before-mentioned forms, it's using at contact form (in the presence of component CB Contact 1.1) and login form (in the
presence of login module of CB 1.2).

PoC:

The PoC for this Insufficient Anti-automation vulnerability was provided to developers. Everyone who want can create such PoC from exploit provided in
above-mentioned article from MoBiC project.

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