badmk.blogg.se

“After a candidate string of digits has been assembled, unCaptcha organically (with uniform timing randomness between each character) types the solution into the field and clicks the ‘Verify’ button.” “After performing phonetic mapping on each of the individual speech recognition services’ predictions, we ‘ensemble’ their responses to obtain a single answer,” researchers wrote. Next, using free online speech-to-text services they are able to identify the audio word challenge.

This triggers the download of the sound file. First, researchers select the audio option of the reCaptcha services using browser automation software. “Visually impaired users are incapable of solving these visual captchas, prompting the creation of audio captchas,” the researchers explain.Īccording to the research paper, unCaptcha combines free speech-to-text engines online and advanced phonetic mapping techniques. In the case of unCaptcha, the method doesn’t rely on the image portion of the challenge, rather it identifies digits or words spoken in an audio clip.

“We evaluate unCaptcha using over 450 reCaptcha challenges from live websites, and show that it can solve them with 85.15 percent accuracy in 5.42 seconds, on average,” wrote authors of the UM paper (PDF) Kevin Bock, Daven Patel, George Hughey and Dave Levin. ReCaptcha is Google’s name for its own technology and free service that uses image, audio or text challenges to verify a human is signing into an account. CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart.

Google introduced reCaptcha in 2014 to most of its public services in an effort defeat bots and scripts that can speedily register hundreds of free web-service accounts at a time. The researchers created a tool called unCaptcha that is able to abuse the audio challenge option of Google’s reCaptcha V2 service. Google’s reCaptcha service has been cracked by a group of University of Maryland researchers who devised an automated attack that can break the service with 85 percent accuracy.