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Wednesday, April 29, 2009

Why You Should Use reCAPTCHA to Protect Online Polls

This week Time Magazine announced the results of their Time 100, a listing of the most influential people over the last year. In the past this list has included Barack Obama, Steve Jobs, and Al Gore. This year’s winner: “moot,” the creator of an underground bulletin board called 4chan. Not many people had heard of moot before, so it’s no surprise to say that that the poll was completely manipulated by members of the site he created. At first, the poll had almost no protection against abuse, so members of 4chan wrote a program to vote for moot millions of times :)

Although Time Magazine eventually decided to implement reCAPTCHA on their poll, it was unfortunately too late. Before Time added reCAPTCHA, members of 4chan had written a program that was able to submit over 20 million votes. After Time added reCAPTCHA, the ballot-stuffing program completely stopped working, and the members of 4chan were forced to spend thousands of human hours typing reCAPTCHAs by hand. Through all this effort (some of them singlehandedly spent 40+ hours per week typing CAPTCHAs), they were only able to submit about 200,000 more votes after Time implemented reCAPTCHA. 200,000 votes is a small number compared to the number of votes other candidates got.

Use reCAPTCHA from the start on your polls and you will significantly raise the bar for spammers to be effective.