Network Security

Black Hat: Breaking SSL network transactions

By making a simple change, a fake SSL certificate can be created and used to persuade users that it is safe to enter their credit card information on a merchant site.

At a presentation Wednesday at the Black Hat conference in Las Vegas, researcher Dan Kaminsky said that because of a weakness in the SSL signing process, certification is unlikely to work in the near future. In SSL, there is no way to properly attribute responsibility to a security issue, he said.

“Hundreds of people can have the same certificate name with SSL,” he said. “Anyone can register any name; there is little control over names.”

He argued that a better approach to authentication of the web would be to rely on Domain Name Service (DNS), specifically the secure version DNSSEC.

“DNS is 25 years old – it scales, it work,” Kaminsky said. “DNS, for example, could be used to serve encryption keys. Every node on the internet goes through DNS.”

No protocol is perfectly secure, but the main problem relates to MD2, a commonly used cryptographic hash function, Kaminsky said.

“MD2 should not be trusted for validation,” he said. And because of this, “the foundations of chained authentication on the internet are broken. Rather than a focus on the users, an MD2 attack would let you log into servers.”

Browser vendors and certificate authorities have essentially agreed to eliminate MD2, mainly heeding warnings that it will be prone to being broken within 18 months, said Kaminsky.

“The current system backs you into a corner,” he said. “We must fix the problem – we cannot just leave it broken.”

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