SAD DNS Explained - Defeating Source Port Randomization with Fragmentation

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JulioHM

Active member
Oct 25, 2020
36
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SAD DNS Explained

The recent UDP feature of packet fragmentation has brought back to life an old DNS attack that was previously mitigated by port randomization.

As is often the case in computer security, old attacks become new again when attackers discover new capabilities. In 2012, researchers Amir Herzberg and Haya Schulman from Bar Ilan University discovered that it was possible for a remote attacker to defeat the protections provided by source port randomization. This new attack leveraged another feature of UDP: fragmentation. For a primer on the topic of UDP fragmentation, check out our previous blog post on the subject by Marek Majkowski.