VoIP: Attacks & Countermeasures in the Corporate World

© Sense of Security 2007 www.senseofsecurity.com1 AusCERT - May 2007

VoIP:Attacks & Countermeasures in the Corporate World

VoIP:Attacks & Countermeasures in the Corporate World

© Sense of Security 2007 www.senseofsecurity.com2 AusCERT - May 2007

VoIP Security

Agenda

• Introduction

• Typical VoIP Network Architecture

• Anatomy of VoIP Attacks

• Demo of a few VoIP Attacks

• Countermeasures

© Sense of Security 2007 www.senseofsecurity.com3 AusCERT - May 2007

VoIP Security

Introduction

• Historically trends and advances in IT outpace security requirements. e.g. 802.11 Wireless. VoIP is the same.

• Tools are becoming more readily available.

• Many of the threats against VoIP are the same threats inherited from the data networking world.

e.g. eavesdropping, mitm, replay etc.

© Sense of Security 2007 www.senseofsecurity.com4 AusCERT - May 2007

VoIP Security

Key Threats

• Denial of Service

– attacks against availability

• Eavesdropping

- unauthorised interception of voice packets

• Impersonation – masquerading as a handset or a piece of VoIP infrastructure

© Sense of Security 2007 www.senseofsecurity.com5 AusCERT - May 2007

VoIP Security

Disclaimer

The techniques demonstrated are not vendor specific.

Our attacks are against an “out of the box” or “default”implementation of VoIP.

We are not responsible for what you do with the tools and techniques demonstrated!

© Sense of Security 2007 www.senseofsecurity.com6 AusCERT - May 2007

VoIP Security

Typical Cisco VoIP Implementation

UTILSTAT

DUPLEXSPEED

SYSTEMRPS

CATALYST 35503

4

5

6

7

8

9

10

11

12

1

2

15

16

17

18

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23

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13

14

1 2

Cisco Call Manager v4.X

IP Phone #1x 1000

IP Phone #3x 3000

IP Phone #2x 2000

VoiceVLAN 6

DataVLAN 2

1 2ABC

3DEF

4 5JKL

6MNOGHI

7 8TUV

9WXYZPQRS

* 0OPER

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7941 SERIESCISCO IP PHONE

© Sense of Security 2007 www.senseofsecurity.com7 AusCERT - May 2007

VoIP Security

Anatomy of Attack – Impersonation

• Step 1: Determine MAC address of handset

• Step 2: Change MAC address on PC

• Step 3: Use Softphone to make a call as that extension

© Sense of Security 2007 www.senseofsecurity.com8 AusCERT - May 2007

VoIP Security

Anatomy of Attack - Eavesdropping

• Step 1: Gather initial information

• Step 2: Get access to voice VLAN

• Step 3: Locate phone targets

• Step 4: Execute ARP poisoning attack and record voice call

© Sense of Security 2007 www.senseofsecurity.com9 AusCERT - May 2007

VoIP Security

Information Gathering

• Cisco phone information disclosure

• IP addresses: DHCP, Call Manager, TFTP, DNS Servers

© Sense of Security 2007 www.senseofsecurity.com10 AusCERT - May 2007

VoIP Security

• Plug into the PC port and sniff!

© Sense of Security 2007 www.senseofsecurity.com11 AusCERT - May 2007

VoIP Security

Get on the Voice Network

• Use the info we have gathered to get on the Voice VLAN.

• Configure the network adapter to tag all ethernet frames with the voice VLAN.

• Voila! We are on the voice VLAN.

• Now we can attack any system on the voice network.

© Sense of Security 2007 www.senseofsecurity.com12 AusCERT - May 2007

UTILSTAT

DUPLEXSPEED

SYSTEMRPS

CATALYST 35503

4

5

6

7

8

9

10

11

12

1

2

15

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1 2

VoIP Security

MITM Attack – ARP Theory

© Sense of Security 2007 www.senseofsecurity.com13 AusCERT - May 2007

Attackers PCIP: 10.6.0.40MAC: D

VoIP Security

MITM Attack - ARP Poisoning Theory

UTILSTAT

DUPLEXSPEED

SYSTEMRPS

CATALYST 35503

4

5

6

7

8

9

10

11

12

1

2

15

16

17

18

19

20

21

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13

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1 2

IP Phone #3IP: 10.6.0.30MAC: C

IP Phone #2IP: 10.6.0.20MAC: B

© Sense of Security 2007 www.senseofsecurity.com14 AusCERT - May 2007

VoIP Security

MITM Attack – Execution

• Start Cain & Abel and configure ARP poisoning.

• Cain & Abel also has the capability to record a call.

• Sit back and wait!

© Sense of Security 2007 www.senseofsecurity.com15 AusCERT - May 2007

VoIP Security

Game Over!

© Sense of Security 2007 www.senseofsecurity.com16 AusCERT - May 2007

VoIP Security

Some Attack Possibilities..

• Telephone banking / Voicemail PIN disclosure• Insertion of audio into conversation• Real-time voicemail capture

© Sense of Security 2007 www.senseofsecurity.com17 AusCERT - May 2007

VoIP Security

Compromising the PIN

• Telephone banking requires a user to enter a customer number and PIN using the touchpad.

• Each number pressed sends a unique tone which is interpreted by the end system.

© Sense of Security 2007 www.senseofsecurity.com18 AusCERT - May 2007

VoIP Security

© Sense of Security 2007 www.senseofsecurity.com19 AusCERT - May 2007

VoIP Security

• But which buttons were pressed?

© Sense of Security 2007 www.senseofsecurity.com20 AusCERT - May 2007

VoIP Security

Countermeasures

Cisco Switch:• Enable DHCP Snooping• Enable Dynamic ARP Inspection• Enable IP Sourceguard• Enable Port Security• Implement VLAN ACLs• Implement 802.1x

© Sense of Security 2007 www.senseofsecurity.com21 AusCERT - May 2007

VoIP Security

Countermeasures (cont.d)

Cisco Call Manager: (Not without some side effects!)• Disable Settings button on phone• Disable Span to PC port • Disable Gratuitous ARP• Disable PC Voice VLAN Access• Configure Signaling & Media Encryption!

© Sense of Security 2007 www.senseofsecurity.com22 AusCERT - May 2007

VoIP Security

How Real is the Threat in Australia?

• One Australian organisation suffers a major telephone hack each and every day.

• AusCERT Computer Crime and Security Survey 2006 shows average value of loss of over $60,000.

• The largest phone hack on record is $1.7M.

• 97% not reported due to risk of adverse publicity.

• Threat to phone service - how would your business cope without phones for an entire day?

• Telstra, Optus and Macquarie Telecom have written to clients warning of the dangers and confirming the customer is liable.

© Sense of Security 2007 www.senseofsecurity.com23 AusCERT - May 2007

VoIP Security

Conclusion

• Most current implementations of VoIP are insecure.

• VoIP can be secured with the right know how.

• The only way to know if your implementation is secure is to have it audited by independent experts.

© Sense of Security 2007 www.senseofsecurity.com24 AusCERT - May 2007

VoIP Security

Questions?

Contact:

Jason EdelsteinT: +61 2 9290 4441E: jasone@senseofsecurity.com.auwww.senseofsecurity.com.au