Title
Towards Evaluating the Security of Real-World Deployed Image CAPTCHAs.
Abstract
Nowadays, image captchas are being widely used across the Internet to defend against abusive programs. However, the ever-advancing capabilities of computer vision techniques are gradually diminishing the security of image captchas; yet, little is known thus far about the vulnerability of image captchas deployed in real-world settings. In this paper, we conduct the first systematic study on the security of image captchas in the wild. We classify the currently popular image captchas into three categories: selection-, slide- and click-based captchas. We propose three effective and generic attacks, each against one of these categories. We evaluate our attacks against 10 real-world popular image captchas, including those from tencent.com, google.com, and 12306.cn. Furthermore, we compare our attacks with 9 online image recognition services and human labors from 8 underground captcha-solving services. Our studies show that: (1) all of those popular image captchas are vulnerable to our attacks; (2) our attacks significantly outperform the state-of-the-arts in almost all the scenarios; and (3) our attacks achieve effectiveness comparable to human labors but with much higher efficiency. Based on our evaluation, we identify the design flaws of those popular schemes, the best practices, and the design principles towards more secure captchas.
Year
DOI
Venue
2018
10.1145/3270101.3270104
AISec@CCS
DocType
ISBN
Citations 
Conference
978-1-4503-6004-3
3
PageRank 
References 
Authors
0.66
0
7
Name
Order
Citations
PageRank
Binbin Zhao151.75
Haiqin Weng253.72
Shouling Ji38320.52
Jianhai Chen414016.34
Ting Wang566465.43
Qinming He637141.53
Reheem Beyah730.66