More Browsing Threats Revealed

The odds are good that you have seen a security certificate for a website at least once. These are what your computer uses to figure out if the site is run by a trusted source, or a dirty scammer. For the most part this is a sound system that has helped to keep giving your information on the internet safe for years. Of course, for every shield there is a sword and a new sword has been discovered that may cause problems for security certificates.

Computer EyeIndependent security researchers in California and the Centrum Wiskunde & Informatica (CWI) in the Netherlands, EPFL in Switzerland, and Eindhoven University of Technology (TU/e) in the Netherlands have found a weakness in the Internet digital certificate infrastructure that allows attackers to forge certificates that are fully trusted by all commonly used web browsers.

The result of this weakness is that it is possible to impersonate secure websites and email servers and to perform virtually undetectable phishing attacks, implying that visiting secure websites is not as safe as it should be and is believed to be. What that means is that even if you think that you are on the right site, and the security certificate checkes out with your browser you may still end up being scammed by a phisher. 

When you visit a website whose URL starts with "https" (the 'secure' version of the normal http) , you see a small padlock symbol in the browser window to show you that this site is locked. This indicates that the website is secured using a digital certificate issued by one of a few trusted Certification Authorities (CAs). These CA's go to great lenths to verify a user before they issue a certificate, and then use high level encryption to be sure that the certificates are not stopped during transmission and decoded by a third party. To ensure that the digital certificate is legitimate, the browser verifies its signature using standard cryptographic algorithms. The team of researchers has discovered that one of these algorithms, known as MD5, can be misused to create a false certificate that seems to be real. 

The first significant weakness in the MD5 algorithm was presented in 2004 at the annual cryptology conference "Crypto" by a team of Chinese researchers. They had managed to pull off a so-called "collision attack" and were able to create two different messages with the same digital signature. This initial construction was severely limited, a much stronger collision construction was announced by the researchers from CWI, EPFL and TU/e in May 2007. Their method showed that it was possible to have almost complete freedom in the choice of both messages. This means that someone skilled could create a rogue certification authority (CA) that is trusted by all major web browsers by a commercially available game console.

What does this mean for me and my data?

  Acritical part of the Internet's infrastructure is not safe, and cannot be trusted. A rogue CA, in combination with known weaknesses in the DNS (Domain Name System) protocol, can open the door for virtually undetectable phishing attacks. For example, without being aware of it, users could be redirected to malicious sites that appear exactly the same as the trusted banking or e-commerce websites they believe to be visiting. The web browser could then receive a forged certificate that will be erroneously trusted, and users' passwords and other private data can fall in the wrong hands. Besides secure websites and email servers, the weakness also affects other commonly used software.

What are browser going to do about it? Is there anything that I can do about it? 

"The major browsers and Internet players – such as Mozilla and Microsoft – have been contacted to inform them of our discovery and some have already taken action to better protect their users," reassures Arjen Lenstra, head of EPFL's Laboratory for Cryptologic Algorithms. "To prevent any damage from occurring, the certificate we created had a validity of only one month – August 2004 – which expired more than four years ago. The only objective of our research was to stimulate better Internet security with adequate protocols that provide the necessary security." As for you personally, sorry. This is one of those situations where you just have to let the professionals do what they can. After all you would not try and perform your own surgery.

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