The add-on was developed at the university's School of Computer Science and College of Engineering. According to the university, the Perspectives software not only protects Firefox users against attacks that might occur because of the recently disclosed software flaw in the DNS, but it also defends against some digital-certificate problems that crop up in everyday use.
"When Firefox users click on a website that uses a self-signed certificate, they get a security error message that leaves many people bewildered," said David Andersen, assistant professor of computer science at Carnegie-Mellon University.
Once Perspectives is installed in Firefox, the browser can automatically override the security error page without disturbing the user if the site appears legitimate.
According to information provided by the university, the Perspectives system augments the certificates provided by VeriSign, Comodo and Godaddy, which reduce the risk of man-in-the-middle attacks by authenticating websites.
The Perspectives system, which uses 'notaries' to query the desired site and check authentication information, is said to provide an extra measure of security for sites that don't use certificate authorities but instead use less expensive 'self-signed' certificates.
The university says the system can 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.
Andersen and another researcher Adrian Perrig also issued said that the Perspectives system will provide a defense against man-in-the-middle attacks that might occur in wireless LAN hot spots where users with mobile computers may seek to access public Wi-Fi service but get tricked into communicating with an attacker's computer instead.