December 14, 2008

Security Book Review: "Voice over IP Security"

"Voice over IP Security"
Author: Patrick Park
Editorial: Cisco Press
Publication date: September, 2008
ISBN-10: 1587054698
ISBN-13: 978-1587054693

Summary: General VoIP security overview. Best chapters: SBC's and LI.

Score: 4/5

The book provides a good general overview of VoIP security, covering multiple topics involved on securing a VoIP infrastructure, from network devices to VoIP servers, plus secure VoIP protocols. In my opinion, the best chapters are chapter 8 and 10 & 11, Session Border Controllers (SBC's) and Lawful Interception (LI), respectively; it is difficult to find books covering these topics still today, although these are two of the major areas regarding VoIP security nowadays.

SBC's are the VoIP security element by design and therefore a key device in any VoIP infrastructure. The book covers SBC's types, access and peering, expected SBC functionality and capabilities (such as DoS protection, translation and NAT features, LI, high availability and load balancing, etc) and offers a brief introduction to its architecture design concepts.

Lawful Interception (LI) by law enforcement (LE), or LI by LE :), is one of the main VoIP research topics today, especially when strong security features are added, such as signaling and media encryption, that difficult the interception tasks. The last two chapters cover the fundamentals of LI on VoIP networks (following the Cisco model, as there are three other standards), describing the different elements, fucntions, and interfaces involved. It is a theoretical chapter followed by some practical advice to implement LI, very detailed and Cisco-based.

The book starts with an introductory overview of VoIP, its benefits and drawbacks, and some security concerns. Then it provides another VoIP threat taxonomy, a good generic overview that lacks some VoIP threats and complements (or simply provides another perspective to) the IETF draft and VOIPSA VoIP threat taxonomies. Unfortunately, I have not found yet a classification that consolidates all the different VoIP threats from (IMHO) the right perspective.

Chapter 3 offers an interesting summarized analysis of the main VoIP protocols, how they work, and their main security requirements and features. It covers H.323, SIP, and MGCP; I specially liked the SIP section, with descriptive message captures and flow diagrams. Chapter 5 complements the VoIP protocols with the main network devices in a VoIP environment, their role, and key security requirements. Although chapter 7 extends the security analysis of VoIP protocols, covering authentication and signaling and media encryption, it does not cover the latest key exchange solutions, such as DTLS, ZRTP or MickeyV2, as it is focused mainly on S/MIME.

All these chapters provide a lightweight analysis of VoIP security, not going very much in-depth into any of the topics covered. The book is a good overview reference for the VoIP security novice reader, I guess intended for network and system administrators, law enforcement, or security pros new to VoIP.

VoIP threats, including some attack types and tools, are analyzed on chapter 6. This chapter covers in detail a few VoIP attacks, providing simulation, examples and command line options for widely available attack tools. It allows the reader to see some real attacks in action, although it only shows the tip of the iceberg regarding all the tools and attacks that are possible; please, do not get the feeling that this is all you can do.

Chapter 4 covers cryptography, and in my opinion, it doesn't fit on the book; although crypto is a key aspect to protect VoIP infrastructures, the novice reader can get this info from other sources.

As the book is from Cisco Press, chapter 9 focuses on specific Cisco features and syntax, specially for practical sections that provide configuration details for firewalls, access devices, and the Unified Communication Manager (& Express), formerly CallManager. The info is useful to get an overview of the implementation steps, but do not apply to you if you are using equipment from other vendors.

Overall, it is a generic reference book to start getting involved into the VoIP security world, acquire a general understanding of the main VoIP security threats, target network elements, VoIP protocols, and security solutions. Once again, the SBC and LI sections are my favorites.

UPDATE: Amazon review.

NOTE: I will not publish my reviews on Bookpool anymore due to their hard-to-use interface and review rules.

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Blogger Raul Siles said...

Comment from kelly:
Lawful Interception is an essential part of VoIP. Its very important. The regarding information is very useful in the field of telecommunication. You can visit our useful website lawful interception. Thanks for posting such nice blog.
Thanks Kelly!

4:26 PM  

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