5 DNS Security Extensions DNSSECsecurity.hsr.ch/.../Vorlesungsunterlagen/05-DNSSEC.pdf · Andreas Steffen, 22.10.2013, 5-DNSSEC.pptx 10 DNS Root Servers A VeriSign Inc. B C D E F

Andreas Steffen, 22.10.2013, 5-DNSSEC.pptx 1

Information Security 1 (InfSi1)

Prof. Dr. Andreas Steffen

Institute for Internet Technologies and Applications (ITA)

5 DNS Security ExtensionsDNSSEC



5.1 Kaminsky Attack onthe Domain Name Service


DNS Resolution via Recursive Nameserver


DNS Request


DNS Response


Simple DNS Cache Poisoning


Guessing Query ID and UDP Source Port


The Dan Kaminsky DNS Vulnerability – July 2008



5.2 DNS Root Servers


DNS Root Servers

A VeriSign Inc.

B

C

D

E

F

G

H

I

J

K

L

M

Information Sciences Institute, USC

OperatorIPv4

198.41.0.4

192.228.79.201

192.33.4.12

199.7.91.13

192.203.230.10

192.5.5.241

192.112.36.4

128.63.3.53

192.36.148.17

192.58.128.30

193.0.14.129

199.7.83.42

202.12.27.33

IPv6

2001:503:BA3E::2:30

#

2001:478:65::53

-

2001:500:2D::D

-

2001:500:2F::F

-

2001:500:1::803F:235

2001:7FE::53

2001:503:C27::2:30

2001:7FD::1

2001:500:3::42

2001:DC3::35

Cogent Communications

8

1

8

University of Maryland 2

NASA Ames Research Center 12

Internet Systems Consortium Inc. 56

US DoD Network Information Center 6

US Army Research Lab 2

Netnod 43

VeriSign Inc. 69

RIPE NCC 17

ICANN 146

WIDE Project 6

376Total number of servers:


Global Map of Root Servers



5.3 DNS SecurityResource Records


root DNSKEY (KSK)*

* explicit import e.g. via trusted web site

ch. DNSKEY (KSK)

ZSK

ch. DS

DNSSEC Chain of Trust

root

KSK/ZSK

ch. DNSKEY (ZSK)

ZSK

switch.ch. DS switch.ch. DNSKEY (KSK)

KSK/ZSK

switch.ch. DNSKEY (ZSK)

ch. switch.ch.

www.switch.ch. A x.x.x.x

ZSK

switch.ch. NS ns1/ns2

ZSK

KSK/ZSK

root DNSKEY (ZSK)


DNSSEC Resource Records I - DNSKEY

• DNSKEY - DNS Public Key

• Contains a public key used to sign the RRsets of a zone

switch.ch. 81154 IN DNSKEY 256 3 5

AwEAAeCDWwjJO4mXBzayiKf4p7waJ7Ew

eUnsTsAWkxpfELci4iaVdBugzYPfsZIg

9R6TIPky3LoPAPmIjCc2fbFkKnrGI7hJ

jXAGMRwRJIBprFx4BXZSsjsvGb6MGC+e

xHSlXw==

;{id = 64608 (zsk), size = 768b}

• Flags field• 256 -> Zone Signing Key (ZSK)

• 257 -> Key Signing Key (KSK) with secure entry point (SEP) flag set

• Algorithm field• 5 -> SHA-1 with RSA

• 7 -> SHA-1 with RSA & NSEC3 with SHA-1

• 8 -> SHA-256 with RSA

• 10 -> SHA-512 with RSA


DNSSEC Resource Records II - RRSIG

• RRSIG - Resource Record Signature

• Contains a public key signature over a resource record set (RRset)

merapi.switch.ch. 172800 IN A 130.59.211.10

merapi.switch.ch. 172800 IN RRSIG A 5 3 172800

20091128231033

20091029231033

64608 switch.ch.

3KW9YjxdL08FqVYKFSn9

Q4+8U1iYrVCun+J1Ny8Y

IiMC+6oQS/GZwRn2mr+H

MruwEjNB9s7bWGzRmRiR

TATPvS67gxjCiJkSP58P

kGJ1dW3wBaz6r1feGNvz

KhHLhvRe ;{id = 64608}

• Signature Expiration and Inception Fields• The signature is not valid before Inception and after Expiration date.

• Key Tag Field• Contains the key tag of the key which signed the RRset.


DNSSEC Resource Records III - DS

• DS - Delegation Signer

• Signed hash computed over KSK of child zone

switch.ch. 3364 IN DS 43837 5 1

91dcfca519cf8b038441869878cc3610

60200534

switch.ch. 3364 IN DS 43837 5 2

838cef7635952df83311a92b48ae7f19

1ae29484534e38b1ab7b3d0966b9ee55

switch.ch. 3416 IN RRSIG DS 7 2 3600

20091123183442

20091117220724 31034 ch.

LPh8RgXQSqPcdQz6s1PJOjTuopO9RxQg

s1YYCY/CnhYaHxb6ndNBJ7QP20eKN+91

/ULjN4Ep/k9Pgtos979i5OfEXpfLcWcv

rKP1xGvqW4PjP+MT1PDs6uKisEUqGBoQ

p7+nkkzjY+YsDbxtTV+/8uHcSnNmXoMm

SqPms3G0aw4= ;{id = 31034}


DNSSEC Resource Records IV - NSEC

• NSEC – Next Owner Name

• Authenticated denial of existence of an owner name

merapi.switch.ch. 180 IN NSEC mercury.switch.ch.

A PTR AAAA LOC RRSIG NSEC

merapi.switch.ch. 180 IN RRSIG NSEC 5 3 180

20091128231033

20091029231033

64608 switch.ch.

kW1SnXWoJKwOHEG1P3INI83EOGuQ

GujwvBT/MSWVQ+ms/2DXxjQcpt1Z

P07+XI51cc0t7erUUG31KZdmUpXZ

tQzPUJh49jjLh9aTjRiH1xGhlxv5

af+N95JDykRGSOAq ;{id = 64608}

• Proof that there is no name between merapi.switch.ch. and mercury.switch.ch.

• Allows enumeration of complete zone data!!!


DNSSEC Resource Records V - NSEC3

• NSEC3 – Next Owner Name in Hashed Order

• Hashed Authenticated Denial of Existence

h9p7u7tr2u91d0v0ljs9l1gidnp90u3h.org. 691 IN NSEC3

1 1 1 d399eaab

h9rsfb7fpf2l8hg35cmpc765tdk23rp6

NS SOA RRSIG DNSKEY NSEC3PARAM ; flags: optout

h9p7u7tr2u91d0v0ljs9l1gidnp90u3h.org. 691 IN RRSIG NSEC3 7 2

86400 20091202211702 20091118201702 5273 org.

a+CC37hRM7yCFBaZn2SeRgY9h247GXptCuBYf45TwaoR

xvBwTAXPT+UwZ/4hxwc2v7AR7ZZ8UOMiNJvYsl59eFW8

Xtgws4/Aih0fJ2/O8yUHwI695fRf9PrpxXEpqzStjSZP

5arJ1oldDAHcnxgLqdAMW6wnK1FNrslfJblJlmU=

;{id = 5273}

• Proof that there is no name between org. and ???.org.

• Does not allow straight enumeration of zone data!

• Dictionary attacks are possible but expensive.



5.4 DANE


DNS-based Authentication of Named EntitiesDANE (RFC 6698, August 2012)

• DANE defines a TLSA Resource Record

• Certificate Usage0 – CA Certificate Constraint1 – Server Certificate Constraint2 – Trust Anchor Assertion for Private CA3 – Domain Issued Certificate

• Selector0 – Full Certificate1 – Public Key Info (Public Key plus Key Type Information)

• Matching Type0 – Exact Match on Selected Content1 – SHA-256 Hash of Selected Content2 – SHA-512 Hash of Selected Content

Cert. Usage Selector Matching Type

Certificate Association Data


DANE – Verifying Server and CA Certificates

Kool CA

Kool CA

TLS Server

www.hsr.ch

TLS Client

www.hsr.ch

Kool CA

DNS Server

hsr.ch

www.hsr.ch. TLSA 1 0 1

ZSK

SHA-256 Hash

check servercertificate


ZSK

SHA-512 Hash

check CAcertificate

or

private key


DANE – Getting CA Certificate or Public Key

TLS Server

www.hsr.ch

TLS Client

www.hsr.ch

HSR CA

DNS Server

hsr.ch


ZSK

get CAcertificate

HSR CA

HSR CA

orwww.hsr.ch. TLSA 2 1 0

ZSK

get CApublic key

private key


DANE – Verifying Self-Signed Server Certificates

TLS Server

www.hsr.ch

TLS Client

www.hsr.ch

Self

DNS Server

hsr.ch


ZSK

SHA-256 Hash

check servercertificate

private key


DANE – Verifying Raw RSA Keys

TLS Server

www.hsr.ch

TLS Client

DNS Server

hsr.ch


ZSK

SHA-256 Hash

check serverpublic key

private key


DANE – Getting Server Certificate or Public Key

TLS Server

www.hsr.ch

TLS Client

DNS Server

hsr.ch


ZSK

get servercertificate

www.hsr.ch

Self

orwww.hsr.ch. TLSA 3 1 0

ZSK

get serverpublic key

private key



5.5 DNS Root SigningProcess


DNSSEC Root Zone Signing Process

ICANN Vetting and Processing

TLD Operator

DSRecords

DoC NTIA Authorization of Changes

DSRecords

VeriSign Editing and Signing of Root Zone

DSRecords

Root Servers (A, ... , M)

DSRecords

Root ZSK

ZSK


DNSSEC Root Zone Signing Key Signing Process

VeriSignZSK Management

ZSK Private Key

ZSK

ZSK

ICANNKSK Management

KSRKey Signing Request

KSK Private Key

KSK

KSKPublished on Web Site

ZSK

KSK

SKRSigned Key Response


ICANN Key Ceremonies

Tier 1 – Facility – Access Control by Data Center



Tier 4 – Cage – Access Control by Data Center

Tier 5 – Safe Room – Access Control by ICANN

Tier 6 – Safe #1 Tier 6 – Safe #2

Tier 7 – Safe Deposit Box

Crypto Officers‘Credentials

Tier 7 – HSM

KSK Private KeysKey Ceremony

Computer


ICANN Key Ceremonies


Periodic Key Rollover

T-10 T+0 T+10 T+20 T+30 T+40 T+50 T+60 T+70 T+80 T+90

ZSKZSK

post-publish

ZSKpre-publish ZSK ZSK ZSK ZSK ZSK ZSK ZSK ZSK ZSK

ZSKpost-publish

ZSKpre-publish ZSK

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

KSKrevoke+sign

KSKrevoke+sign

KSKpublish

KSKpublish

KSKpublish

KSKpublish

KSKpublish

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

KSKpublish+sign

ZSK Rollover (every 90 days)

Optional KSK Rollover (every 2-5 years or on demand)

RRSIG Validity Period (10 days + 50% overlap)


DNSSEC Deployment (October 22, 2013)

• TLDs signed by root zone:• 13 gTLDs: arpa asia biz cat com edu gov info mil museum net org post

• 81 ccTLDS: ac af ag am at be bg br bz ca cc ch cl co cr cx cz de dk eu fifo fr gi gl gn gr gs hn in io is jp kg ki kr la lb lc li lk lt lu lv memm mn my na nc nf nl nu nz pl pm pr pt pw re ru sb sc sesh si su sx tf th tm tt tv tw tz ua ug uk us wf yt

• 8 IDN ccTLDS: xn--kprw13d xn--kpry57d (台湾 Taiwan)xn--mgbx4cd0ab (مليسيا Malaysia)xn--3e0b707e (한국 South Korea)xn--o3cw4h (ไทย Thailand)xn-l1acc (мон Mongolia)xn-h2brj9c (भारत India)xn--p1ai (рф Russia)

• Signing of major gTLDs:• net: December 2010

• com: March 2011

Documents

5 DNS Security Extensions DNSSECsecurity.hsr.ch/.../Vorlesungsunterlagen/05-DNSSEC.pdf · Andreas Steffen, 22.10.2013, 5-DNSSEC.pptx 10 DNS Root Servers A VeriSign Inc. B C D E F