Please read the links at the bottom of the following link, they're
pretty enlighting indeed.
http://en.wikipedia.org/wiki/Captcha
-----Original Message-----
From: Marian Ion [mailto:marian.ion@e-licitatie.ro]
Sent: Monday, August 29, 2005 3:39 PM
To: victor@outblaze.com; robert@webappsec.org
Cc: websecurity@webappsec.org; webappsec@securityfocus.com
Subject: RE: [WEB SECURITY] Re: Defeating CAPTCHA
Maybe it will not be such a good ideea ... especially if some
mobile communication providers would have some network issues on a
critical moment ... And such a method will be based also on a
pre-defined algorithm, possibly easy to learn, to implement.
On a longer term, maybe a faster implementation of IP6 will
bring some new logging / blocking possibilities (based, for example, on
"sender validation"), supported also by a strict legislation.
Also, applications implementations (including CAPTCHA) based on
artificial intelligence will provide improved security on many IT
aspects. Neural nets are becoming smarter, and due to improved
optimisations brought by genetic algorithms, ants or bees algorithms,
are learning a lot faster than us, especially when discussing on
repetitive tasks.
On short term ... better, non-repetitive CAPTCHAs, based on
random lengths and characters types, with several effects applied on the
generated image, are probably the best way.
Also, the implementation of "expiration" events, based on time
passed without a reply message or manual (or automatic) validation, or
something similar would do good. And also some application filters, in
listing the records, to ignore/eliminate some garbage data.
Marian Ion
-----Original Message-----
From: victor [mailto:victor@outblaze.com]
Sent: Monday, August 29, 2005 1:54 PM
To: robert@webappsec.org
Cc: websecurity@webappsec.org; webappsec@securityfocus.com
Subject: [WEB SECURITY] Re: Defeating CAPTCHA
I was struck by the CAPTCHA issue a while back too, it happens to me
that CAPTCHA reminded me of all these anti-piracy technique that have
been developed over the past 2 decades. Put this special data into
that sector of the disc so pc-tools can't copy it or install this
special cd checker to make sure the cd is not pirated. We all know the
result, finding a crack to all these protection is only a question of
when.
I would say CAPTCHA is too a case of trying to fight intelligent with
more intelligent. which is an endless loop with no true winner. And so
I wonder maybe a true solution to this abuser protection issue lies
somewhere else.
I myself look at the setup this way, all these tool hacker uses depends
on one thing to function, the question being presented as part of the
signup/login procedure, because we must make the question presentable
online and friendly enough for humand to process, it is bound to be
possible to come up with some porgram to come up/brute force the answer.
So in another word, the existence of the question itself has made it
possible for hacker to come up with software to defeat the protection.
In a way, the solution has itself become the problem, so I am thinking
maybe instead of trying to improve it. We should look into eliminating
it.
I can see some good example out there that is going into that
direction. Many online banking service are taking advantage of SMS,
sending user a passkey where they have to use to login to the service.
Or this implementation pay pal has implemented, that debit user's
credit card and ask user to use that sum as some form of passkey as one
of the gentlemen here has pointed out.
These solution are very expensive compare to CAPTCHA but the direction
seems to be more reliable and hack-profe. If a better solution to
CAPTCHA should be found, this maybe one direction you fellow might want
to consider.
Tor.
robert@webappsec.org wrote:
This was linked off of slashdot
(http://it.slashdot.org/article.pl?sid=05/08/24/1629213&tid=172&tid=95)
and explains some of the ways people are breaking CAPTCHA
(http://en.wikipedia.org/wiki/Captcha) based systems.
http://sam.zoy.org/pwntcha/
- Robert
robert_at_webappsec.org
http://www.cgisecurity.com
--
<!---------------------------------------------
Victor
Development Engineer
Outblaze Ltd
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