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Domain Name System Security. Cora Hussey and Roy Shea April 9, 2003. Review of DNS Hierarchy. Review of DNS Query. Review of DNS Record. Threats to DNS. (A) Man in the middle (B) ID guessing and query prediction (C) Corrupt DNS server. Threats to DNS (Continued).
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Domain Name System Security Cora Hussey and Roy Shea April 9, 2003
Threats to DNS • (A) Man in the middle • (B) ID guessing and query prediction • (C) Corrupt DNS server
Threats to DNS (Continued) • (A) Denial of service • (B) No authentication of non-existence • (C) Wildcards
DNS Security Goals • Data origin authentication • Data integrity • Authentication of non-existence
Changes to DNS • New resource records • Signature (SIG) • Key (KEY) • Delegation Signer (DS) • Next (NXT) • New bits in message header • Checking disabled (CD) • Authentic data (AD)
Security Aware Components • Resolver • Verifies digital signatures • Forms authentication chains • Dependent on security aware • recursive name server • proxy • zone • name server
Security Aware Components (Continued) • Stub Resolver • Ideally trusts • recursive name server • channel to recursive name server • Or set the Checking Disabled bit and verify the security chain itself
Security Aware Comonents(Continued) • Zone • Proper setting of TTL and SIG validity periods • Periodically update SIGs, forcing an SOA update • Name Server • Be able to include extended records in response to queries • Key management of zone signing keys and key signing keys
Questions • What attacks are still possible with DNS security? • Are wild cards worth the effort? • Is partial deployment beneficial? • What attacks does DNS security make possible? • Are their better methods to secure DNS?