Sentor
Blockscraping.com What’s scraping? What’s your business? Directory Airline Online property B2B-portals What’s your position? Executive IT Information security Legal Scraping news Prevent scraping Data seeding Scraping FAQ Sentor Services Risk assessment Managed anti-scraping service Scraping consulting About Sentor Contact us

Captchas does not stop scraping

CAPTCHA breaking outsourced

CAPTCHA image from GoogleThe Register has an article about recent troubles for Google with spammers registering free accounts. People in low cost counties is hired to manually break CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart), to create accounts later used to send spam using Googles resources.

CAPTCHAs broken in many ways

CAPTCHA image from YahooNot only humans is used to break CAPTCHAS. Earlier this year it was widely reported that Yahoo's CAPTCHA system was broken with software by security researchers from Russia. They released software able to decode images with a recognition rate of about 35%.

Microsoft also have the same problem with their free mail accounts. Websense reports on how Microsoft Windows Live Mail sign up procedure is broken by malware.

CAPTCHAs does not work to stop scraping. The advances in OCR-technology further accentuates the need for additional scraping mitigation solutions working together with captcha tests.

Scraping news
Turing test

Turing test is a proposal for a test of a machine's capability to demonstrate intelligence. It was proposed by professor Alan Turing in the 1950 paper "Computing machinery and intelligence" where a human tries to decide if she is talking to a machine or not.

Reverse Turing test
A test administered by a computer to decide if the subject is or is not human for example by the use of a CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is some times called a reverse Turing test

© Sentor 2008.