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Security and Disaster Recovery for IP Telephony Systems

IP Presence


IP Presence Featured Article

 

August 02, 2007

Security and Disaster Recovery for IP Telephony Systems

By Mae Kowalke, TMCnet Associate Editor

Mitel
 

Security. It’s a word that can send chills down the back of any IT administrator who manages the IP telephony system for a business or organization. IP telephony offers many benefits, but if the solutions used don’t include adequate safeguards, this new technology can also introduce a host of security holes.

 
One company that takes security very seriously is Mitel (News - Alert), a provider of IP telephony and IP presence solutions. Dan York, chair of Mitel’s product security team, recently spoke with TMCnet about how the company ensures that its clients can protect their businesses without sacrificing the benefits of next-generation telephony.
 
TMCnet: How is security an issue for IP telephony systems different than PSTN systems?
 
DY: In the days of PSTN telephony, all you really had to worry about was the physical security of the phone system. Eavesdropping was a threat if someone connected to your wiring closet, but it was a pretty simple thing to protect against.
 
The challenge that Voice over IP (VoIP) brings is the fact that it's not just the telephony system—it’s everything else. It’s the data network, it’s the operating system the applications are running on, it’s the e-mail servers, it’s the firewalls; it’s a big mish-mash of everything.
 
The challenge in most organizations is that the ‘everything’ is not necessarily owned by one group. It used to be you could just call the corporate communications department and have security taken care of. But now you have to contact the firewall people and the server people and the IT people. The responsibilities have changed and broadened. It’s a very complicated picture with a lot of people involved, and a lot of finger-pointing that can potentially happen. Complexity brings concern, especially for security.
 
The security of a traditional PSTN system involved a physical component; to breach safeguards, somebody had to be physically access your wiring closet or a central office. But with IP telephony, somebody can interject themselves between caller and recipient conceivably from thousands of miles away.
 
TMCnet: What are some of the security threats associated with IP telephony systems?
 
DY: When we talk about security, generally we break it up into five main areas: voice signaling, management interface, APIs, PSTN and TCP/IP network. First, there is the media path associated with voice signaling. Here, eavesdropping is the main concern. Somebody could be listening to the conversation.
 
A larger issue that people don’t necessarily think about as much but is a huge concern for financial institutions is the ability to modify calls. It’s very conceivable—and there are tools out there to help—for someone to intercept a phone conversation and change it. So, instead of a message to a broker being “Buy 10,000 shares,” it could be changed to “Sell 10,000 shares.”
 
Degraded quality is also an issue. If you attack VoIP systems with the appropriate denial of service, you can degrade voice quality to where it’s worse than a cellphone.
 
The second area of attack is signaling. When you pick up and dial, you're sending signaling to the IP-PBX (News - Alert). Here, as with the media path, you’ve got the potential for denial of service attacks, hang ups, disconnects, and impersonation. Toll fraud also can be a problem. There were some large cases last year in which people were arrested for allegedly bilking service providers out of millions of dollars by hijacking call control and channeling their own calls through the system.
 
For both the media path and signaling, encryption is a simple fix. (More on this later.)
 
Another potential area of attack area is the management interface—both Web-based and otherwise. Web-based management is new. In the PSTN days, the management console was directly connected to the PBX (News - Alert) so all you had to do was physically go to the console to make changes. With an IP-PBX, you can be hundreds of miles away doing remote administration. That's great for administrators, but it’s also great for an attacker. You’ve got to make sure that the management is secure.
 
A third element to consider in the security equation is APIs (Application Programming Interfaces). Part of the strength of IP telephony is that it offers unified communications and the ability to build other applications on top of platforms. But, if the APIs aren’t secure, somebody could start messing around with the system.
 
Fourthly, for security purposes PSTN access must still be considered. This is something the newer entrants into the field are trying to figure out. The voice can go over IP, but the system still connects to the PSTN at some point. VoIP security brings with it all of the security problems of traditional telephony plus all the security problems associated with the world of data. Now there are twice the security issues.
 
A final element to consider is the underlying TCP/IP network. It used to be that the PBX was just bolted to the wall somewhere and you forgot about it; now, because phones are end-points on the data network, you've got to make sure the IP telephony system is part of your patch management plan and other network maintenance tasks. You never had to do that before.
 
TMCnet: How does Mitel define a 'secure communications solution'?
 
DY: When we talk about a secure communications solution, it means our main IP-PBX (the Mitel 3300 IP Communications Platform, or 3300 ICP for short) is secure by default. One of the things we do is encrypt the entire voice and signaling path. When you plug in a Mitel phone system, by default it’s configured with encryption across all of the voice and across all the sets. It's not an added option, it’s not something you have to go and enable or buy extra licenses. It’s just there, secure by default.
 
This means that, right out of the box, the Mitel phone system offers a base level of security across the phones, voice signaling, call control, management interfaces and APIs; all of those elements are all locked down. Encryption doesn't solve everything, but it solves many things and makes other things harder.
 
All of Mitel’s phones also include a built-in firewall to fight back against common types of network attacks.
 
Because security for IP telephony has to protect against toll fraud, impersonation, feature access and other possible holes, Mitel’s solutions include the following protection:
 
1. Voice encryption
2. Signaling encryption
3. Firewalls
4. Management authentication
5. Tightly authenticated XML APIs
 
TMCnet: How does Mitel use encryption to safeguard its IP telephony solutions?
 
DY: We use the industry standard Secure RTP (SRTP) for voice. We encrypt it by default. For our signaling encryption we use 128-bit AES (advanced encryption standard). We also generate new session keys for each phone conversation so they can't be replayed.
 
As mentioned earlier, encryption is on by default, whereas solutions from some of our competitors require that you enable it. This default encryption is built into all Mitel phones; you're not forced to buy a specific executive phone.
 
Also, the number of users we say a system will support is the number of users--with full encryption. Some competing systems may say they support a thousand users but with encryption enabled it might really be only 800.
 
TMCnet: What is authentication and how does Mitel use this technique for IP telephony security?
 
DY: The phones have to authenticate somehow--there has to be some way to prevent any random set to connect to the 3300 ICP or any other platform. When you provision Mitel sets, you have to enter in a unique identifier into the 3300 ICP for each phone. The set sends that identifier across the encrypted call control connection for authentication.
 
One layer of authentication for Mitel’s IP telephony system, then, occurs at the device level. A second layer can be added through hot-desking, which Mitel supports. With hot-desking, each user has an extension and a PIN. When the user goes to a phone, her or she enters in their extension and password to use the phone.
 
It is possible to set up a phone that, by default, has just basic class of service for dialing internally and calling 911. It can't do anything outside that. But, when somebody goes up to the phone, and logs in using hot-desking, the phone takes on their persona and the user has access to message waiting light, voicemail, hotkeys, etc. That’s an extra layer of authentication.
 
TMCnet: How do hot-desking and other security features help with disaster recovery and business continuity?
 
DY: Hot-desking has a really neat effect when you talk about disaster recovery and business continuity. You can log into a phone from anywhere on the network. Let’s say an office has to close because of some kind of disaster. Flood, fire, snowstorm--pick your disaster. Employees can’t get there. But, if they’re at home and have a broadband connection and a Mitel teleworker phone, they can log in to their hot-desk extensions. Now they can have access to all of their settings and voicemail, and can be reached; business can keep on going.
 
Also, using Mitel’s IP telephony solutions employees can be relocated very easily. This is something IP does and that we never had in traditional telephony without paying for insanely expensive connections. Even during disasters, business can keep on going. For example, let’s say there’s a fire at a call center and agents have to leave the building. Those agents can go home, log in to their phones, and have access to ACD queues and get calls just as if they were in the office.
 
Part of the strength Mitel offers is that our architecture is all about a distributed network of systems. There can be a 3300 ICP at headquarters and one in each of the branch offices. They can all be networked together. The beautiful part about that is, if a system goes down, the phones can automatically fail over to another office. Business isn't interrupted. That's our resiliency feature.
 
Mitel now also supports SIP trunking. You can have multiple SIP trunks to provide different types of PSTN access. You're no longer restricted to just having PSTN connectivity in one location; you could have it in multiple locations, coming conceivably across multiple Internet connections. With SIP trunking, you can set up multiple PSTN gateways.
 
Mitel offers a product called Mitel Wireless LAN (WLAN) Stand—a wireless, local area network stand. This product can function as either a client—on an existing WiFi (News - Alert) network—or as an access point. Let's say your office burns down and you want to rapidly deploy a small office to cover business in that region. You could ship six of phones with WLAN Stands to a hotel and hook them up to the broadband Internet connection there. One of those phones could be the access point for the other ones, which would act as clients. Since all of the phones could be teleworker sets, it would be possible to very rapidly deploy a whole small office of five or six phones to replace the functionality of an office that was incapacitated in some way.
 
With IP telephony, geography doesn't matter. Phones can be set up, and employees deployed, anywhere.
 

To learn more about Mitel’s security and disaster-recovery features, please visit the company’s TMCnet.com channels, IP Telephony and IP Presence.

 
Mae Kowalke previously wrote for Cleveland Magazine in Ohio and The Burlington Free Press in Vermont. To see more of her articles, please visit Mae Kowalke’s columnist page. Also check out her Wireless Mobility blog.





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