DNS Patches May Break Some Things…

I just had a quick conversation with an IT technician who alluded to the idea that more than Zone Alarm may be broken by the new port randomization behaviors of “patched DNS”. These fundamental changes to the ports allocated for DNS traffic may confuse existing firewalls and other filtering devices that are unaware of the changes to DNS behaviors.

For example, if you have filtering devices that specific port ranges defined for egress or ingress of DNS traffic, especially if you are using a non-stateful device, this configuration may need to be changed to allow for the greater port range applied to the “patched DNS” setup. Systems that are also “DNS aware” might not expect the randomization of the ports that the patching is creating. As such, filtering devices, especially at the perimeter may well need to be reconfigured or upgraded as well to allow for continued operation of unimpeded DNS traffic.

There may be SEVERAL other nuances that become evident in some environments as the patch process for the DNS issue continues to evolve. Stay tuned to stateofsecurity.com and other security venues for information and guidance as it becomes available.

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