Attacking CAPTCHAs for Fun and Profit

Introduction
A “Completely Automated Public Turing test to tell Computers and Humans Apart,” or “CAPTCHA,” is used to prevent automated software from performing actions that degrade the quality of service of a given system. CAPTCHAs aim to ensure that the users of applications are human and ultimately aidin preventing unauthorized access and abuse.To analyze the strength of CAPTCHA implementations on the Internet, research was conducted covering several high traffic websites. During the research CAPTCHA protection on three types of forms were
 
reviewed:
• Registration pages
• Forgotten password functionality
• User comment fields for blog posts, news articles, and other content
 
The vulnerabilities identified during the research were classified into three broad categories: breaching client-side trust, manipulating server-side implementation, and attacking the CAPTCHA image. In this paper, we will look at the interesting and the most common vulnerabilities identified during the research.
 
Download PDF: http://www.mcafee.com

HTML5 Top 10 Threats Stealth Attacks and Silent Exploits

Abstract
 HTML5 is an emerging stack for next generation applications. HTML5 is enhancing browser capabilities and able to execute Rich Internet Applications in the context of modern browser architecture. Interestingly HTML5 can run on mobile devices as well and it makes even more complicated. HTML5 is not a single technology stack but combination of various components like XMLHttpRequest (XHR), Document Object model (DOM), Cross Origin Resource Sharing (CORS) and enhanced HTML/Browser rendering. It brings several new technologies to the browser which were not seen before like localstorage, webSQL, websocket, webworkers, enhanced XHR, DOM based XPATH to name a few. It has enhanced attack surface and point of exploitations for attacker and malicious agents. By leveraging these vectors one can craft stealth attacks and silent exploits, it is hard to detect and easy to compromise.  

• ClickJacking & Phishing by mixing layers and iframe
• CSRF and leveraging CORS to bypass SOP
• Attacking WebSQL and client side SQL injection
• Stealing information from Storage and Global variables
• HTML 5 tag abuse and XSS
• HTML 5/DOM based XSS and redirects
• DOM injections and Hijacking with HTML 5
• Abusing thick client features
• Using WebSockets for stealth attacks
• Abusing WebWorker functionality   

Above attack vectors and understanding will give more idea about HTML5 security concerns and required defense. It is imperative to focus on these new attack vectors and start addressing in today’s environment before attackers start leveraging these features to their advantage. 

Download PDF:  https://media.blackhat.com