Deciphering the Simple Machines Forum audio Captcha

Type securityvulns
Reporter Securityvulns
Modified 2008-04-21T00:00:00


The Simple Machine’s Forum audio Captcha that has been hardened from attack. I have contacted SMF about this flaw and it has been verified.

I go into greater detail of how i am able to break this captcha here:

Exploit Code:

This captcha has been broken before and exploit code is available here: . The fix was to add a randomly generated static.

I was able to write code to decipher the audio file using a Fuzzy Logic comparison . The comparison is the Hamming Distance between the original audio file and the damaged one generated by the Captcha.