full-disclosure - DoS attacks via captchas

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Message-ID: <000101cacf26$c5679fd0$010000c0@ml>
Date: Sun, 28 Mar 2010 23:58:00 +0300
From: "MustLive" <mustlive@...security.com.ua>
To: <full-disclosure@...ts.grok.org.uk>
Subject: DoS attacks via captchas

Hello Full-Disclosure!

Last week I wrote an article DoS attacks via captchas
(http://websecurity.com.ua/4052/) and recently I wrote it's English version.

I published article to The Web Security Mailing List, where you can read it:

DoS attacks via captchas
http://www.webappsec.org/lists/websecurity/archive/2010-03/msg00083.html

Captchas must protect web sites against automated requests. But as I showed
in my project Month of Bugs in Captchas
(http://websecurity.com.ua/category/mobic/), they badly handle with it, due
to multiple Insufficient Anti-automation vulnerabilities, which allow to
bypass captchas. Besides, captchas can lead to DoS attacks on the sites.

In the article I told about different ways to conduct DoS attacks on the 
sites which are using captchas. It must be interesting as for security 
community, as for admins and web developers. So everyone, who interested in 
this subject, can read the article.

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

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