Linux Kernel: New Side-Channel Risk for DNS Cache Poisoning Attack

A recent research paper by a team at University of California, Riverside, shows the existence of previously overlooked side channels in the Linux kernels that can be exploited to attack DNS servers. According to the researchers, the issue with DNS roots in its design, that never really took security as a key concern and that made it extremely hard to retrofit strong security features into it.

While DNS security features are available, including DNSSEC and DNS cookies, they are not widely deployed due to backward compatibility, say the researchers. Instead, the only approach to make DNS more secure has been the randomization of UDP ports, known as ephemeral ports, with the aim to makes it harder for an attacker to discover them.

As a result of this, several attacks to DNS have been discovered in the past, including the recent SAD DNS, a variant of DNS cache poisoning that allows an attacker to inject malicious DNS records into a DNS cache, thus redirecting any traffic to their own server and becoming a man-in-the-middle (MITM).