Defeating audio captcha systems
Hi all,
Some days ago I wrote an advisory which demonstrates how the Peter's
Math Antispam Spinoff plugin for wordpress
(http://www.theblog.ca/math-anti-spam) can be defeated by its audio file.
It's hard to summarize, you better read the advisory, but in a very
small nutshell, the flaw its about not using any kind of distortion on
the audio clip, which makes it easily identificable by a script.
Here is the link:
http://docs.google.com/View?docid=df36cd52_19xzmkwqcg
I'm sure you will find the advisory inspirational, as the approach is
applicable to many other capthas, and anti-script methods.
Regards
Jose