Comments on: Captcha is failing! Is there another way

By: Shoaib

Shoaib — Sat, 24 Nov 2007 12:07:37 +0000

hxxp://shoaib.no-ip.org/iptables.sh

that should cover pretty much all of new zealand

By: john

john — Sat, 24 Nov 2007 06:42:57 +0000

Iptables is too much work. I’ve done that before to stop spammers hammering my box. Regarded too much work.

We have a email validation, its still not stopping registrations.

The new captcha seems to be working as I’ve had no spam registrations since. fingers crossed.

John

By: Shoaib

Shoaib — Fri, 23 Nov 2007 21:04:27 +0000

iptables ftw!

By: john

john — Thu, 22 Nov 2007 23:53:00 +0000

Hmmm Google groups is sounding appealing…

I installed a more advanced captcha and hopefully that will offset the default actions to stop the scripts from doing their thing…

By: M Freitas

M Freitas — Thu, 22 Nov 2007 23:52:01 +0000

In addition to hidden form (which should be discarded if filled because humans wouldn’t do it), try doing a different thing: people should enter their email addresses requesting to join… Send an encoded URL containing the email address. Whe the actual registration comes in check that the e-mail used matches the one in the encoded URL. This is what I do on Geekzone and simply reduces spammers a lot…

By: Stephen Judd

Stephen Judd — Thu, 22 Nov 2007 22:05:09 +0000

Another angle: just set up a Google Group, and let them deal with it…

By: Stephen Judd

Stephen Judd — Thu, 22 Nov 2007 21:17:26 +0000

This may be useful to you:

http://www.codinghorror.com/blog/archives/001001.html

Basically, some captchas simply suck and are susceptible to automated OCR – others don’t and aren’t.

FWIW, other strategies include:
- multiple forms hidden by Javascript/CSS (don’t allow users that post to the hidden form)
- change default variable names
- charge default posting URLs
- add extra steps, eg mandatory preview
- queue the first comment from a new user for moderation

There’s no solution that doesn’t involve customisation – automated attackers focus their efforts on “out of the box” configurations.

By: john

john — Thu, 22 Nov 2007 20:16:05 +0000

We’re using the defualt captcha as installed by phpBB. I’m note sure if we can overload it with something else.

By: kirill volkov

kirill volkov — Thu, 22 Nov 2007 20:15:44 +0000

Have you seen this article (Has CAPTCHA Been “Broken”?): http://www.codinghorror.com/blog/archives/001001.html
It gives good comparison of different captchas.

By: Glen Barnes

Glen Barnes — Thu, 22 Nov 2007 19:43:10 +0000

What type of CAPTCHA are you using? I was wondering if you have tried the RE-CAPTCHA as I wanted to see if this was any better (digitise books AND hopefully stop SPAM).