ION Bucharest - Deploying DNSSEC
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This document summarizes Dan York's presentation on deploying DNSSEC. It discusses how DNSSEC helps ensure the integrity of DNS data by using digital signatures to authenticate DNS responses, preventing cache poisoning and man-in-the-middle attacks. It provides examples of normal DNS interactions versus attacks, and how DNSSEC establishes a chain of trust. The presentation also covers the current state of DNSSEC deployment, how it works in combination with TLS/SSL through DANE, and business reasons for organizations to deploy DNSSEC.
ION Bucharest - Deploying DNSSEC
- 1. Internet Society © 1992–2016 The role of the Internet Society (this report describes the timeline of activities of the Internet Society from the submission of the proposal to NTIA in March 2016 until September 30, 2016) The IANA Stewardship Transition Kathy Brown President & CEO October 6, 2016 Presentation title – Client name 1
- 2. Internet Society © 1992–2016 ION Bucharest October 12, 2016 Dan York, CISSP DNSSEC Program Manager – york@isoc.org Deploying DNSSEC 2
- 3. Trusted Internet 3 Trust in privacy of information (ex. encryption) Trust in online identity systems (ex. Kantara) Trust in network communication (ex. TLS, DANE) Trust in Internet identifiers (ex. DNSSEC) Trust in the Internet’s core infrastructure (ex. MANRS) Trust in cryptography (ex. Cryptech)
- 5. Email Hijacking CERT-CC researchers have identified that someone was hijacking email by using DNS cache poisoning of MX records Could be prevented by DNSSEC deployment CERT-CC (Sept 10, 2014): — https://www.cert.org/blogs/certcc/post.cfm?EntryID=206 Deploy360 blog post (Sept 12, 2014): — http://wp.me/p4eijv-5jI
- 6. What Problem Is DNSSEC Trying To Solve? DNSSEC = "DNS Security Extensions" • Defined in RFCs 4033, 4034, 4035 • Operational Practices: RFC 4641 Ensures that the information entered into DNS by the domain name holder is the SAME information retrieved from DNS by an end user. Let's walk through an example to explain… 6
- 7. A Normal DNS Interaction 7 Web Server Web Browser https://example.com/ web page DNS Resolver example.com? 1 2 3 4 10.1.1.123 Resolver checks its local cache. If it has the answer, it sends it back. example.com 10.1.1.123 If not…
- 8. A Normal DNS Interaction 8 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4 example.com NS .com NS example.com?
- 9. DNS Works On Speed First result received by a DNS resolver is treated as the correct answer. Opportunity is there for an attacker to be the first one to get an answer to the DNS resolver, either by: Getting to the correct point in the network to provide faster responses; Blocking the responses from the legitimate servers (ex. executing a Denial of Service attack against the legitimate servers to slow their responses) 9
- 10. Attacking DNS 10 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 192.168.2.2 4 Attacking DNS Svr example.com 192.168.2.2 example.com NS .com NS example.com?
- 11. A Poisoned Cache 11 Web Server Web Browser https://example.com/ web page DNS Resolver 1 2 3 4 192.168.2.2 Resolver cache now has wrong data: example.com 192.168.2.2 This stays in the cache until the Time-To-Live (TTL) expires! example.com?
- 12. How Does DNSSEC Help? DNSSEC introduces new DNS records for a domain: • RRSIG – a signature ("hash") of a set of DNS records • DNSKEY – a public key that a resolver can use to validate RRSIG A DNSSEC-validating DNS resolver: Uses DNSKEY to perform a hash calculation on received DNS records Compares result with RRSIG records. If results match, records are the same as those transmitted. If the results do NOT match, they were potentially changed during the travel from the DNS server. 12
- 13. A DNSSEC Interaction 13 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 DNSKEY RRSIGs 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4 example.com?
- 14. A DNSSEC Interaction 14 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 DNSKEY RRSIGs 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4 example.com NS DS .com NS DS example.com?
- 15. The Global Chain of Trust 15 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 DNSKEY RRSIGs 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4 example.com NS DS .com NS DS example.com?
- 16. Attempting to Spoof DNS 16 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 DNSKEY RRSIGs 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 Attacking DNS Svr example.com 192.168.2.2 DNSKEY RRSIGs example.com NS DS .com NS DS example.com?
- 17. Attempting to Spoof DNS 17 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 DNSKEY RRSIGs 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 SERVFAIL 4 Attacking DNS Svr example.com 192.168.2.2 DNSKEY RRSIGs example.com NS DS .com NS DS example.com?
- 18. What DNSSEC Proves: • "These ARE the IP addresses you are looking for." (or they are not) • Ensures that information entered into DNS by the domain name holder (or the operator of the DNS hosting service for the domain) is the SAME information that is received by the end user. 18 10/12/2016
- 19. The Two Parts of DNSSEC 19 Signing Validating ISPs Enterprises Applications DNS Hosting Registrars Registries
- 20. What DNSSEC Proves: • "These ARE the IP addresses you are looking for." (or they are not) • Ensures that information entered into DNS by the domain name holder (or the operator of the DNS hosting service for the domain) is the SAME information that is received by the end user. 20 10/12/2016
- 21. DNSSEC Validation – Current State • About 15% of all global DNS queries validated • ~20% of all European DNS queries validated • All major DNS resolvers support DNSSEC validation – often with a simple config change 21 http://stats.labs.apnic.net/dnssec
- 22. DNSSEC Validation – Romania 22http://stats.labs.apnic.net/dnssec
- 23. DNSSEC Validation – Romania 23http://stats.labs.apnic.net/dnssec
- 24. DNSSEC Signing - The Individual Steps 24 Registry Registrar DNS Operator (or ”DNS Hosting Provider”) Domain Name Registrant • Signs TLD • Accepts DS records • Publishes/signs records • Accepts DS records • Sends DS to registry • Provides UI for mgmt • Signs zones • Publishes all records • Provides UI for mgmt • Enables DNSSEC (unless automatic)
- 25. DNSSEC Signing – Current State • Most TLDs now signed • including “new gTLDs” • Common DNS servers all support DNSSEC • Second-level domain support ranges from 100% in .BANK and 89% in .GOV down to < 1% in .COM • Still small % overall. 25 https://www.internetsociety.org/deploy360/d nssec/maps/
- 26. DNSSEC Signing – Second-level domains 26https://rick.eng.br/dnssecstat/
- 28. Why Do I Need DNSSEC If I Have TLS? • A common question: why do I need DNSSEC if I already have a SSL certificate? (or an "EV-SSL" certificate?) • Transport Layer Security (TLS), sometimes called by its older name of “SSL”, solves a different issue – it provides encryption and protection of the communication between the browser and the web server 28
- 29. The Typical TLS Web Interaction Web Server Web Browser https://example.com/ TLS-encrypted web page DNS Resolver example.com? 10.1.1.1231 2 5 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4
- 30. The Typical TLS Web Interaction Web Server Web Browser https://example.com/ TLS-encrypted web page DNS Resolver 10.1.1.1231 2 5 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4 Is this encrypted with the CORRECT certificate? example.com?
- 31. What About This? 31 Web Server Web Browser https://www.example.com/ TLS-encrypted web page with CORRECT certificate DNS Server www.example.com? 1.2.3.4 1 2 Firewall (or attacker) https://www.example.com/ TLS-encrypted web page with NEW certificate (re-signed by firewall)
- 32. Problems? 32 Web Server Web Browser https://www.example.com/ TLS-encrypted web page with CORRECT certificate DNS Server www.example.com? 1.2.3.4 1 2 Firewall https://www.example.com/ TLS-encrypted web page with NEW certificate (re-signed by firewall)
- 33. Problems? 33 Web Server Web Browser https://www.example.com/ TLS-encrypted web page with CORRECT certificate DNS Server www.example.com? 1.2.3.4 1 2 Firewall https://www.example.com/ Log files or other servers Potentially including personal information TLS-encrypted web page with NEW certificate (re-signed by firewall)
- 34. Issues • A Certificate Authority (CA) can sign ANY domain. • Now over 1,500 CAs – there have been compromises where valid certs were issued for domains. • Middle-boxes such as firewalls can re-sign sessions. 34
- 35. DNS-Based Authentication of Named Entities (DANE) Q: How do you know if the TLS (SSL) certificate is the correct one the site wants you to use? A: Store the certificate (or fingerprint) in DNS (new TLSA record) and sign them with DNSSEC. An application that understand DNSSEC and DANE will then know when the required certificate is NOT being used. Certificate stored in DNS is controlled by the domain name holder. It could be a certificate signed by a CA – or a self-signed certificate. 35
- 36. A Powerful Combination • TLS = encryption + limited integrity protection • DNSSEC = strong integrity protection • How to get encryption + strong integrity protection? • TLS + DNSSEC = DANE 36
- 37. DANE 37 Web Server Web Browser w/DANE https://example.com/ TLS-encrypted web page with CORRECT certificate DNS Server 10.1.1.123 DNSKEY RRSIGs TLSA 1 2Firewall (or attacker) https://example.com/ TLS-encrypted web page with NEW certificate (re-signed by firewall)Log files or other servers DANE-equipped browser compares TLS certificate with what DNS / DNSSEC says it should be. example.com?
- 38. DANE Success – Not Just For The Web SMTP 1000+ SMTP servers with TLSA records http://dane.sys4.de/ - testing service XMPP (Jabber) 400+ servers client-to-server & server-to-server https://xmpp.net/reports.php#dnssecdane 38
- 39. DANE Resources DANE Overview and Resources: http://www.internetsociety.org/deploy360/resources/dane/ IETF Journal article explaining DANE: http://bit.ly/dane-dnssec RFC 6394 - DANE Use Cases: http://tools.ietf.org/html/rfc6394 RFC 6698 – DANE Protocol: http://tools.ietf.org/html/rfc6698 39
- 40. DNS Privacy 40
- 41. DNS Privacy • Issue - Queries from local DNS “stub resolver” (in PC, laptop, smartphone) to local DNS resolver are sent in clear • Surveillance of those queries can be revealing • Solution – Encrypt the connection
- 42. DNS Privacy 42 Web Server Web Browser https://example.com/ web page DNS Resolver 10.1.1.123 1 25 6 DNS Svr example.com DNS Svr .com DNS Svr root 3 10.1.1.123 4 example.com NS .com NS example.com?
- 43. DNS Privacy – Work Underway Now • IETF “DPRIVE” Working Group • New standards emerging– DNS queries over TLS • Expect to see implementations in software and operating systems in the future
- 44. Business Reasons For Deploying DNSSEC • TRUST – You can be sure your customers are reaching your sites – and that you are communicating with their servers. • SECURITY – You can be sure you are communicating with the correct sites and not sharing business information with attackers, ex. email hijacking. • INNOVATION – Services such as DANE built on top of DNSSEC enable innovative uses of TLS certificates. • CONFIDENTIALITY – DANE enables easier use of encryption for applications and services that communicate across the Internet. 44
- 45. Three Requests For Attendees 1. Deploy DNSSEC validation (or ask your IT team / network operator) 1. Sign your domains • Work with your registrar and/or DNS hosting provider to make this happen. 2. Help promote support of DANE protocol • Let browser vendors and others know you want to use DANE. If you use SSL, deploy a TLSA record if you are able to do so. Help raise awareness of how DANE and DNSSEC can make the Internet more secure.
- 46. Visit us at www.internetsociety.org Follow us @internetsociety Galerie Jean-Malbuisson 15, CH-1204 Geneva, Switzerland. +41 22 807 1444 1775 Wiehle Avenue, Suite 201, Reston, VA 20190-5108 USA. +1 703 439 2120 Thank you. 46 Dan York Senior Content Strategist – york@isoc.org