The robustness of a new CAPTCHA

CAPTCHA is a standard security technology that presents tests to tell computers and humans apart. In this paper, we examine the security of a new CAPTCHA that was deployed until very recently by Megaupload, a leading online storage and delivery website. The security of this scheme relies on a novel segmentation resistance mechanism. However, we show that this CAPTCHA can be segmented using a simple but new automated attack with a success rate of 78%. It takes about 120 ms on average to segment each challenge on a standard desktop computer. Categories and Subject Descriptors

• Type: Conference
• Year: 2010
• Where: EUROSEC
• Authors: Ahmad Salah El Ahmad, Jeff Yan, Lindsay Marshall
• Keywords: Captcha, EUROSEC 2010, Security Privacy, Segmentation Resistance Mechanism, Standard Security Technology