2
The World’s Network – the Domain
Name System
+ Internet Protocol address uniquely identifies laptops or phones or other devices
+ The Domain Name System matches IP addresses with a name
+ IP routing and DNS are the underpinning of unified
Internet

3
A sample DNS query
Where is www.iana.org?
192.0.2.1

4
Making the DNS Secure
+ A computer sends a question to a DNS server, like
“where is IANA.org?”
+ It receives an answer and assumes that it is correct.
+ There are multiple ways that traffic on the Internet can be intercepted and modified, so that the answer given is false.

5
Receiving the Wrong Answer

Poisoning a Cache
+ Attacker knows iterative resolvers may cache
+ Attacker
+ Composes a DNS response with malicious data about a targeted domain
+ Tricks a resolver into adding this malicious data to its local cache
+ Later queries processed by server will return malicious data for the life of the cached entry
+ Example: user at My Mac clicks on a URL in an email message from try@loseweightfastnow.com
My Mac
My local resolver
What is the IPv4 address for loseweightfastnow.com?
I’ll cache this response… and update www.ebay.com
loseweightfastnow.com IPv4 address is 192.168.1.1
ALSO www.ebay.com is at
192.168.1.2
ecrime name server
6

7
DNS Security (DNSSEC)
+ Protects DNS data against forgery
+ Uses public key cryptography to sign authoritative zone data
+ Assures that the data origin is authentic
+ Assures that the data are what the authenticated data originator published
+ Trust model also uses public key cryptography
+ Parent zones sign public keys of child zone
(root signs TLDs, TLDs sign registered domains…
7

8
Public Key Cryptography in
DNSSEC
Authority signs zone data with private key
Authorities must keep private keys secret!
Sign with
Private key
DNS
Data
Signed DNS
Data
+
Digital signatures
Publish
Authoritative server
8

9
Public Key Cryptography in
DNSSEC
Authority publishes
public key so that any recipient can decrypt to verify that “the data are correct and came from the right place”
Validate with
Public key
Validating recursive server
9
Signed
Zone
Data
Authoritative server

10
ICANN’s Role in DNSSEC
Deployment
+ Manages root key with VeriSign and trusted international representatives of Internet community
+ Processes requests for changes of public key and other records from registries at top of DNS
+ Educates and assists Internet community with
DNSSEC
+ Implements DNSSEC on its own domains

11
Obstacles to Broader DNSSEC
Adoption
+ Browser and/or Operating System support
+ DNSSEC support from domain name registration service providers (registrars, resellers)
+ Misconceptions regarding key management, performance, software/hardware availability and reliability

12
•
Fast pace of deployment at the TLD level
• Deployed at root
• Supported by software
•
Growing support by ISPs
• Required by new gTLDs

Inevitable widespread deployment across core Internet infrastructure