The History of DNS Vulnerabilities and the Cloud
Summary: A Unit 42 article reviews two decades of DNS cache poisoning vulnerabilities, explaining how an attacker who can send packets to a resolver can inject a fake answer during the resolution window and redirect clients to an attacker-controlled IP address. It traces the mitigations: transaction IDs were originally an ascending counter, randomizing the 16-bit field made guessing 65,536 times harder, and a 1 Mbit/s attacker could still reach a better-than-50% success rate in about 18 tries within a two-second window.
Key Takeaway: A 16-bit transaction ID leaves only 65,536 possibilities, and the article's own arithmetic shows an attacker on a 1 Mbit/s link needing roughly 18 attempts to beat a 50% success threshold - so a poisoned cache entry redirects every client that resolves that name until it times out.
Read the original at Unit 42 Palo Alto Networks ↗
- Topics
- Vulnerabilities & Patching
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