Apple servers still vulnerable to DNS flaw

A month after a critical flaw in the Internet's Domain Name System was first reported, security experts are warning that updates introduced by Apple last week may not go far enough to combat the threat.

The DNS flaw allows an attacker to execute a cache poisoning attack, where traffic to a legitimate domain name is redirected to a malicious one after an attack on a DNS server.

[ Read more about Apple finally patching the dangerous DNS flaw. ]

The user can type in the correct name for a Web site, but get a fake one instead, which can enable a phishing attack. While some users might notice if they're directed to a odd-looking web page, many people could be successfully fooled.

Ncircle security analyst Andrew Storms warns, thought, that in the patch released in an attempt to address this problem last week, Apple has not implemented tough enough counter-measures to the threat.

"The current countermeasure to this DNS cache poisoning vulnerability is to introduce increased entropy by forcing randomization of the query ID and the source port," the experts said. "Essentially, making it all the more difficult to spoof the DNS response. However, it appears that Apple forgot something. The client libraries on my OSX 10.4.11 system, post patch install, still does not randomize the source port."

The experts warn that the problem is a huge potential danger for Apple, saying, "it matters most that they patch the client libraries since there are so few OS X recursive servers in use.

"The bottom line is that despite this update, it appears that the client libraries still aren't patched."