USENIX Security2026
DNS Cache Poisoning Like it's 2006
Omer Ben-Simhon, Amit Klein
Abstract
The Domain Name System (DNS) underpins virtually all Internet services, making the integrity of DNS resolution critical to security and availability. We present a comprehensive study of a novel class of DNS cache poisoning attacks against BIND 9, the most widely deployed open-source DNS resolver. Our attack focuses on two key capabilities that set it apart from most prior work: (1) reliably predicting both critical challenge parameters -the UDP source port and TXID -whereas most existing attacks target only one; and (2) performing this prediction entirely from the client side, without attacker-operated authoritative servers for attacker domains, which to our knowledge is a first. We achieve this by exploiting weaknesses in BIND's pseudo-random number generation, enabling highly reliable prediction even under realistic network conditions. In addition to the client-side-only techniques, we also develop server-side techniques which are needed in order to attack the older 9.18 branch of BIND 9. We evaluate our attacks and demonstrate practical success rates across multiple BIND 9 release branches and configurations. All vulnerabilities were responsibly disclosed to the Internet Systems Consortium (ISC) and the FreeBSD Project, leading to two patches and CVEs and acknowledgments.