WebApp Sec mailing list archives

Re: CAPTCHA


From: arvind doraiswamy <arvind.doraiswamy () gmail com>
Date: Wed, 26 Jan 2011 12:53:15 +0530

A question though. It should be possible to write a 'targeted bot'
which doesn't fill up those fields..rt? Or did I miss something?

Arvind


-----Original Message-----
From: Robin Wood
Sent: Monday, January 24, 2011 7:49 PM
To: Shang Tsung
Cc: webappsec () securityfocus com
Subject: Re: CAPTCHA


On 24 January 2011 15:11, Shang Tsung <shangtsung71 () gmail com> wrote:
We are planning to use a CAPTCHA in order to stop spam engines from
filling our Online Forms. From a quick research I made, I found there
are good and there are bad types of CAPTCHA.

Does anyone know if there are any standard and secure implementations
of CAPTCHA that we can use?

Any good articles on the subject?

I hate captchas, always have so I use a reverse captcha on sites that
I build. You add a field to the form with name and id of email. You
then give it a label that says "Please leave blank" and hide them both
with CSS. Most people won't see them because the CSS works, even if
they do see them they read the message and obey. Spam engines on the
other hand spot the email field and happily fill it in. You then
silently drop any contact forms with values in the email field.

Normal humans aren't affected and you trick most generic bots.

Robin



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