bugtraq - Re: Vulnerability in CB Captcha for Joomla and Mambo

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Date: Thu, 15 Apr 2010 12:11:29 -0700
From: Susan Bradley <sbradcpa@...bell.net>
To: MustLive <mustlive@...security.com.ua>
Cc: bugtraq@...urityfocus.com
Subject: Re: Vulnerability in CB Captcha for Joomla and Mambo

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
>
>