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Practical Crypto Attacks Against Web Applications

cracking, cryptography, web application
Juliano Rizzo, Thai Duong
Black Hat EU 2010
Indexed on
Mar 26, 2013
File name
File size
744.0 KB

In 2009, we released a paper on MD5 extension attack ([1]), and described how attackers can use the attack to exploit popular web sites such as Flickr, Vimeo, Scribd, etc. The attack has been well-received by the community, and made the Top Ten Web Hacking Techniques of 2009 ([2]). In the conclusion of that paper, we stated that we have bexen carrying out a research in which we test-run a number of identified practical crypto attacks on random widely-used software systems. To our surprise, most, if not all, can be attacked by one or more of well-known crypto bugs. In this talk, we present the latest result of that research, where we choose another powerful crypto attack, and turn it into a new set of practical web hacking techniques. We show that widely used web development frameworks and web sites are using encryption wrongly that allow attackers to read and modify data that should be protected. It has been known for years in cryptography community that encryption is not authentication. If encrypted messages are not authenticated, data integrity cannot be guaranteed which makes systems vulnerable to practical and dangerous chosen-ciphertext attacks. Finally, we list several popular web development frameworks and web sites that are vulnerable to Padding Oracle attacks, including, but not limited to, eBay Latin America, Apache MyFaces, SUN Mojarra, Ruby On Rails, etc. These are all 0-day vulnerabilities. We show that even OWASP folks can't get it right, how can an average Joe survive this new class of vulnerabilities? We strongly believe that this is just the tip of the iceberg, and the techniques we describe in this research would uncover many more vulnerabilities for years to come.

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