Eliminating eavesdropping

The growth of shared Wi-Fi and other wireless computer networks has increased the risk of eavesdropping on internet communications.

But now, researchers at Carnegie Mellon University's School of Computer Science and College of Engineering have devised a low cost system that can thwart these so-called 'Man-in-the-Middle' (MitM) attacks.

The system, called Perspectives, can also protect against attacks related to a recently disclosed software flaw in the Domain Name System (DNS), the internet phone book used to route messages between computers.
   
The researchers - David Andersen, assistant professor of computer science, Adrian Perrig, associate professor of electrical and computer engineering and public policy, and Dan Wendlandt, a PhD student in computer science - have incorporated Perspectives into an extension for the popular Mozilla Firefox v3 browser.

It can be downloaded free of charge at www.cs.cmu.edu/~perspectives/firefox.html.
   
Perspectives employs a set of friendly sites, or 'notaries' that can aid in authenticating websites for financial services, online retailers and other transactions requiring secure communications. By independently querying the desired target site, the notaries can check whether each is receiving the same authentication information, called a digital certificate, in response. If one or more notaries report authentication information that is different than that received by the browser or other notaries, a computer user would have reason to suspect that an attacker has compromised the connection.
   
Certificate authorities, such as VeriSign, Comodo and GoDaddy, already help authenticate websites and reduce the risk of MitM attacks. The Perspectives system provides an extra layer of security in those cases but will be especially useful for the growing number of sites that do not use certificate authorities and instead use less expensive 'self-signed' certificates.
   
Andersen said: 'When Firefox users click on a website that uses a self-signed certificate, they get a security error message that leaves many people bewildered.' Once Perspectives has been installed in the browser, however, it can automatically override the security error page without disturbing the user if the site appears legitimate.
   
The system can also detect if one of the certificate authorities may have been tricked into authenticating a bogus website and warn the Firefox user that the site is suspicious. Perrig added: 'Perspectives provides an additional level of safety to browse the internet.'