VoIP Security Best Practices

Bogdan MaternaCTO & VP Engineering

VoIPshield Systems

Session: U3-03 04/02/2009

VoIP Security Overview

• Voice over IP (VoIP) inherits the same security threats as the IP data network, plus some new ones

• Traditional IT security products are not equipped to address the new challenges associated with securing voice systems

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• Follows the data networks security history but VoIP is different than traditional data security:

• VoIP is a real-time, mission-critical service

• Voice-specific malicious activities

• VoIP presents new vectors of attack

• Applications (existing H/W and new S/W based vendors)

• Devices (wireline and wireless)

• Protocols (standard and proprietary)

• Still in the early stages – a few known incidents, more unpublished cases

• Research a cornerstone of VoIP and UC security

• Vulnerabilities, threats, exploits

• Signatures

• Zero day

Current State of VoIP Security

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Typical Enterprise PBX Deployment

Call ManagerGateway

Soft ClientsCorporate Data Network

Hard Phones

IP Trunk

Switch

PSTN Trunk

Access and Trunk Traffic

• One physical interface (1 Gbit/sec) supports both access and trunking traffic

• In large installation an additional physical interface might be used to provide dedicated IP trunking

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VoIP based Call Center

ACD

PBX

Call Recorder

Web Application Servers(HTML, VXML,

E-mail, and Chat)

CTI & Reporting Server

CRM

Customer

Internet Voice Mail

Confidential informationusage, maintenance, collection

Customer

IVR

AgentsSoftphone

Confidential informationtransmission

• Confidential information is collected , stored and transmitted through VoIP infrastructure

• Complex call flows, infrastructure and outsourcing creates potential for security

breaches

• Large call volumes6

•Software related (introduced by a VoIP vendor)

•Configuration related (introduced by the user of VoIP)

•Protocol related (inherent protocol issues – SIP, UNIStim, Skinny, H323)

•Composite (combination of the above)

•Device level (related to a particular device/application such as IP PBX)

•System level (related to the VoIP infrastructure components and topology)

•Unidirectional or duplex (related to flow of data and information)

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VoIP Vulnerabilities and Exploits

VoIP Protocol Layer

VoIP Application Layer(Call Manager, PBX, Voice Mail, gateway, softphone…)

Singling Protocols(Unistim, Skinny, SIP, …)

Transport Protocols(RTP, UDP, …)

VoIP Supporting Services Layer(DNS, DHCP, Web, Database, Authentication servers…)

OS and Network Layer(Linux, Unix, Windows)

ConfigurationDatabase

PBX Call Manager Remote/Local

Remote/Local

Remote/Local

Remote/Local

Remote/Local

Hundreds of permutations and attack vectors

Device Level Vulnerabilities and Exploits

Security Layers

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Converged Networks Security

Protection

Prevention

Mitigation

Converged Data, Voice and Video Network

Prevention•Compliance assessment•Vulnerability and Risk Assessment•Patching

Protection•Perimeter (Firewall, IPS, SPIT)•Internal (HIPS, NAC, Encryption)

Mitigation Security attack impact mitigation

Pro

cess

es

Peo

ple

Processes Modified to accommodate VoIP specific security requirements

People Education and awareness training

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Corporate Firewall

VIPS/Anti-SPIT

IP PBX/Softswitch/Call Manager

PRI / BRI / Analog Lines

Internet

IP PBX/Softswitch/Call Manager

PSTN

EnterpriseVoIP

Network

VoIP Phones

PCs/VoIP Soft Phones

VA/CMVIPS/VNAC

Corporate SBC

Corporate VoIP Network

Corporate Data Network

Departmental

IPS/NAC Departmental

IPS/NAC

Departmental

IPS/NAC

Data

Calls

VIPS/VNAC

SIM

Enterprise VoIP Security Infrastructure

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VoIP Service

Provider

VoIP Best Practices

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Best Practices – VoIP Risk Assessment• Pre-deployment or existing VoIP installations

• Identify threats that could adversely affect critical operations and assets

• Estimate the probability that such threats being exploited based on historical information and judgment of experts

• Identify and rank the value, sensitivity, and criticality of the operations and assets that could be affected. Determine which operations and assets are the most important.

• Estimate, for the most critical and sensitive assets and operations, the potential losses or damage

• Identify the best actions to mitigate or reduce the risk. These actions can include implementing policies, procedures and technical or physical controls

• Document the results and develop an action plan

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Best Practices – Risk Assessment Critical Success Factors

• Obtain C level, IT , security and telecommunication department support

• Involve VoIP equipment vendor(s)Designate primes for various activities

• Define procedures

• Involve business and VoIP/UC technical experts

• Keep the scope well defined and focused

• Document and maintain results

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Best Practices – Pre-deployment1. Execute Risk Assessment process

2. Create VoIP Security Architecture Design & Implementation Document

3. Make it an integral part of VoIP RFP process

4. Create a lab infrastructure corresponding to the production VoIP deployment

5. Run vulnerability assessment on the VoIP equipment

6. Install and test VoIP security applications identified in (1)

7. Run effectiveness assessment on the VoIP security apps

8. Put it all together and run false/positive realistic tests:

• Blocking attacks

• Blocking legitimate traffic

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Best Practices – Existing Installations

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1. Execute Risk Assessment process

2. Create VoIP Security Architecture Design & Implementation Document

3. Provide business case for deploying VoIP security

4. Run vulnerability assessment on the production VoIP equipment. Fix the issues by patching, reconfiguration or network tuning

5. Create a lab infrastructure corresponding to the production VoIP deployment

6. In the lab install and test VoIP security applications identified in (2)

7. In the lab run effectiveness assessment on the VoIP security apps

8. In the lab put it all together and run false/positive realistic tests:

• Blocking attacks

• Blocking legitimate traffic

9. Run pilots/stage the security apps deployment in production

Best Practices – Specific Recommendations1. Be proactive :

– Acquire VoIP VA tool or procure VoIP VA Services

– Make sure VoIP is part regulatory compliance framework

2. Protect your infrastructure

– Use Session Border Controller as a access point for SIP trunks

– Deploy VoIP IPS with VoIP specific signatures sets and detection engines

– Deploy VIPS sensors in remote locations

– Encryption/Authentication where it makes sense

– Use VPN to carry traffic amongst the sites if it provides required QoS

– Consider Data Leakage Protection on VoIP

– For large number of home office or travelling employees consider deployment of VNAC functionality

– If SPIT is a risk you identified you should acquire anti-SPIT appliance

Best Practices – Specific Recommendations3. Manage PBX configuration:

– Default passwords, barrier codes, access codes

– Employees who are no longer with the company

– Local administrators

– Administrative access

– User profiles

– Adds/Moves

– Toll fraud

Best Practices – Operationalize VoIP Security

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Write polices and procedures how to manage, for example:– Passwords, barrier codes, access codes, etc.

– Accounts owned by people who are no longer with the company: end-point PBX profiles, voice mail, remote access, admin access, etc.

– Changes made by VoIP administrators

– admin passwords

– Vulnerability assessment process

– VoIP remote access policy

– Usage of softclients on the laptops

– Contractors, business partners access to VoIP infrastructure

Best Practices – Operationalize VoIP Security

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Integrate VoIP security infrastructure with the existing management tools and processes, for example:

– Integration with SIM/SEM systems

– Tracking changes in PBX configuration

– User adds and moves

– Patching process

– Relationship with VoIP Service Provider(s)

– Integration with email, IM and other UC applications

Best Practices – Advice

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Don’t think you are secure because:– You use only PSTN trunks

– You implemented VLAN based separation of VoIP and data

– You have a solid data security infrastructure

– You encrypted all the traffic

– Your VoIP equipment vendor told you so

Thank You

bmaterna@voipshield.comwww.voipshield.com