A major DNS vulnerability is affecting Domain Name Servers, which serve as the backbone of the Internet. But while many companies have put out updates that patch the flaw, Apple has yet to update OS X Server.
Known as cache poisoning, the DNS flaw allows an attacker to introduce forged DNS information into the cache of a caching nameserver. If a DNS server is affected by this attack, you would not go to the site you intended to on the Web.
For instance, if you typed macworld.com in your Web browser, you would expect to visit Macworld’s Web site. But, if the DNS cache has been attacked, you would end up wherever the attacker wanted you to go.
Domain Name Servers translate host names like Macworld.com to IP addresses like 220.127.116.11. In short, DNS allows us all to surf the Web in the way we’ve become accustomed. If DNS servers go down, Web sites simple become unavailable.
The idea of cache poisoning is not new, but because it affects the very heart of the Internet, it is a dangerous vulnerability. The flaw not only affects servers, but any user that relies on Mac OS X Server for the DNS information.
There are two published OS X Server fixes for DNS vulnerability — one from Glenn Fleishman and the other by Chuq von Rospach.