Time Synchronization Security

using IPsec and MACsec

Appeared in ISPCS 2011

Tal Mizrahi

Israel Networking Seminar

May 2012

Time Synchronization Security

• Time synchronization is used for various applications.

• Securing the time protocol is a must for securing the applications

that use it.

• IEEE 1588 standard: Precision Time Protocol (PTP).

• IEEE 1588 is challenging to secure:

– A large number of nodes involved in the protocol.

– Hop-by-hop data modification.

• IEEE 1588 - Annex K: experimental security appendix.

2 Time Synchronization Security using IPsec and MACsec

Agenda

• Brief overview of IPsec, MACsec, and Annex K.

• The IPsec and MACsec scenarios.

• Attacker types.

• Effectiveness of each attacker in the IPsec and MACsec

scenarios, Annex K.

• Summary and comparison.

• Conclusion.

3 Time Synchronization Security using IPsec and MACsec

IPsec

• A suite of security protocols defined by the IETF (RFC 4301 –

architecture).

• Two main functions:

– Integrity protection using Authentication Header (AH).

– Confidentiality using Encapsulating Security Payload (ESP).

• Both functions support:

– Integrity protection using Integrity Check Value (ICV).

– Replay protection using Sequence Number.

• Both functions support:

– Tunnel mode.

– Transport mode.

• IPsec AH encapsulation.

4

Next Header1B

Payload Len1B

Reserved2B

Security Parameters Index (SPI)4B

Sequence Number Field4B

Integrity Check Value – ICV (variable length)

IPv4 Header

Ethernet Header

IP Header (tunnel mode)

IP Payload

Ethernet FCS4B

Protected

by ICV

Partly

Protected

by ICV

Time Synchronization Security using IPsec and MACsec

Time Synchronization Security using IPsec and MACsec

MACsec

• IEEE 802.1AE – MAC security protocol.

• IEEE 802.1X – authentication, key exchange.

• Supports both encrypted and non-encrypted mode.

• Integrity protection using Integrity Check Value (ICV).

– L2 header protected by ICV.

• Replay protection using Sequence Number.

• MACsec encrypted packet.

5

MACsec Ethertype2B

MACsec Header6B / 14B

MAC SA

MAC DA

Ethernet Payload

Ethernet FCS4B

Pro

tecte

d

by IC

V

En

cry

pte

d

Integrity Check Value – ICV 16B

Ethertype2B

IEEE 1588 Annex K

• Experimental annex in IEEE 1588-2008 (v2).

• Provides data integrity using symmetric key scheme.

• Authentication TLV includes:

– Integrity Check Value (ICV).

– Replay protection using replayCounter.

• Annex K authenticated packet.

6

PTP Header

PTP Payload

Authentication TLV

IPv4/IPv6 + UDP Headers (optional)

Ethernet Header

Ethernet FCS4B

Protected

by ICV

Time Synchronization Security using IPsec and MACsec

PTP Security – the IPsec Scenario

• Can be used when PTP is transported over an IP network.

• Network-to-network configuration.

• IPsec can be used in encrypted (ESP) or authenticated (AH) mode.

• Either dedicated tunnel for time sync, or single tunnel for all traffic.

• Typical example: Femtocells in 3GPP.

7

Operator

Network

Master

ClockSecurity

GW

Public

Network

Security

GW

IPsec TunnelSlave

Customer

Network

Time Synchronization Security using IPsec and MACsec

PTP Security – the MACsec Scenario

• Can be used in L2 networks.

• Either with/without encryption.

• All data is secured on a hop-by-hop basis.

• Typical example: Audio and Video Bridging (AVB).

8

L2

Network

L2 Bridge

MACsec TunnelMACsec Tunnel Master

ClockSlave

Time Synchronization Security using IPsec and MACsec

Typical Attackers

• Mary – internal man-in-the-middle (MITM).

• Jeanie – internal injector.

• Emma – external MITM.

• Enya – external injector.

9

Master

ClockSecurity

GW

Enya

Security

GW

Trusted

Network

Secure TunnelSecure Tunnel

Security

GWSecure Tunnel

Security

GW

Trusted

Network

Emma Mary (2)

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

Time Synchronization Security using IPsec and MACsec

Enya – WHAT can Enya do?

10

Master

ClockSecurity

GW

Enya

Security

GW

Trusted

Network

Secure TunnelSecure Tunnel

Security

GWSecure Tunnel

Security

GW

Trusted

Network

Emma Mary (2)

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

• Cryptographic Performance Attack.

• L2/L3 DoS attacks. M

AC

sec

IPse

c

15

88

An

nex K

• • •

• •

Time Synchronization Security using IPsec and MACsec

Emma – WHAT can Emma do?

11

Master

ClockSecurity

GW

Enya

Security

GW

Trusted

Network

Secure TunnelSecure Tunnel

Security

GWSecure Tunnel

Security

GW

Trusted

Network

Emma Mary (2)

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

• Packet Interception and Removal.

• Packet Delay Manipulation.

• Cryptographic Performance Attack.

• L2/L3 DoS attacks.

MA

Cs

ec

IPse

c

15

88

An

nex K

• • •

• • •

• • •

• •

Time Synchronization Security using IPsec and MACsec

Jeanie – WHAT can Jeanie do?

12

Master

ClockSecurity

GW

Enya

Security

GW

Trusted

Network

Secure TunnelSecure Tunnel

Security

GWSecure Tunnel

Security

GW

Trusted

Network

Emma Mary (2)

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

• Spoofing.

• Replay Attack.

• Rogue Master Attack.

• L2/L3 DoS attacks.

• Spoofing.

• Replay.

• Rogue Master Attack.

• L2/L3 DoS attacks.

Time Synchronization Security using IPsec and MACsec

Jeanie (1) – WHERE can Jeanie be found?

13

Secure TunnelSecure Tunnel

Secure TunnelSlave 2

Master

ClockSecurity

GW

Security

GW

Trusted

Network

Secure Tunnel

Security

GW

Trusted

Network

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

Master

Clock

Slave 1

IPsec Tunnel

Jeanie (2)

• Jeanie 1 is relevant

specifically in the IPsec

scenario.

• Network-to-network scheme.

IPsec scenario.

MACsec scenario /

Annex K

Time Synchronization Security using IPsec and MACsec

Mary – WHAT can Mary do?

14

Master

ClockSecurity

GW

Enya

Security

GW

Trusted

Network

Secure TunnelSecure Tunnel

Security

GWSecure Tunnel

Security

GW

Trusted

Network

Emma Mary (2)

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

• Packet Interception and Manipulation.

• Packet Delay Manipulation.

• Packet Interception and Removal.

• Spoofing.

• Replay.

• Rogue Master Attack.

• L2/L3 DoS attacks. Time Synchronization Security using IPsec and MACsec

Mary – WHERE can Mary be found?

15

Secure TunnelSecure Tunnel

Secure Tunnel

Mary (2)

Slave 2

Master

ClockSecurity

GW

Security

GW

Trusted

Network

Secure Tunnel

Security

GW

Trusted

Network

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Slave 2

Master

Clock

Slave 1

IPsec Tunnel• Mary 1 is relevant specifically

in the IPsec scenario.

• Network-to-network scheme.

• Mary 2 is relevant specifically

in the MACsec scenario.

• Hop-by-hop scheme.

IPsec scenario.

MACsec scenario /

Annex K Time Synchronization Security using IPsec and MACsec

Time Synchronization Security using IPsec and MACsec

Master

ClockSecurity

GW

Enya

Security

GW

Secure TunnelSecure Tunnel

Security

GWSecure Tunnel

Security

GW

Emma Mary (2)

Jeanie (2)

Jeanie (1)

Mary (1)Slave 1

Analysis Summary

16

MACsec Scenario IPsec

Scenario

IEEE 1588 Annex

K

Ch

ara

cte

ris

tic

s

Network L2

typically LAN

L3

typically public

network

Any

Security approach Hop-by-hop Network-to-network Hop-by-hop

Accuracy +

(TCs/BCs)

~

(no TCs/BCs)

+

(TCs/BCs)

Th

rea

ts

L2/L3 DoS Attack Prevention + - -

Internal attackers in the

“trusted network”

(Jeanie 1, Mary 1)

+ - +

Internal MITM attacks in

intermediate nodes (Mary 2) - + -

Conclusion

• IPsec and MACsec are used in different topologies and

scenarios.

• Two complementary building blocks for securing time

synchronization.

• Intermediate solutions in the absence of a standard security

solution for PTP.

• Hybrid solutions can be used in certain topologies.

17

Hybrid

Security

GWPublic

Network

Security

GW

IPsec Tunnel

Master

Clock

L2

Network

MACsec Tunnel

Slave

Time Synchronization Security using IPsec and MACsec

Thanks!