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Toll fraud is alive and well

Fraudsters look to VoIP and unified communications as new attack vectors

By Adam Boone, special to Network World
October 01, 2009 08:03 PM ET
This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.

Network World - Almost as long as there have been toll calls there has been toll fraud. From phone phreakers to corrupt insiders to external hackers, fraudsters have found a way to make crime pay. But three trends related to this old crime are bringing it to the forefront once again, creating headaches for enterprise managers.

One, it is increasingly obvious that toll fraud perpetrators are highly organized, operating multinational syndicates engaging in multi-million dollar fraud. Two, the widespread deployment of VoIP and unified communications (UC) is opening new attack vectors. And three, the victims of toll fraud are no longer primarily service providers, but enterprises of all types and sizes.

In June, the U.S. government announced it had broken up a $55 million toll fraud ring that was operating internationally and targeting enterprise PBXs. While details on the fraud are still emerging, according to a grand jury filing, the ring operated primarily out of Italy and Spain. The alleged ringleaders paid hackers in the Philippines to target enterprises in the United States and hack the companies' PBXs, often using techniques as simple as brute force password cracking.

The fraudsters then controlled the hacked PBXs and, through various methods, used them to make long-distance calls. They monetized the scheme by opening public long-distance calling centers in Italy and Spain, presumably charging individuals to make long-distance calls.

U.S. law enforcement officials say the fraudsters ran up 12 million minutes in telephone usage, which was estimated to represent approximately $55 million in fraudulent charges across the various enterprises and service providers affected by the scheme.

It is clear that technically sophisticated groups are making use of ubiquitous telephony and data infrastructures to raise the ease and frequency of these crimes to new levels. And they are finding increasingly creative ways to cash out as they exploit their victims.

Old Crime, new network, new targets

While the $55 million toll fraud ring appears to have targeted traditional PBXs, taking advantage of inadequate password practices, the new world of VoIP telephony poses equally new fraud risks.

In fact, a VoIP network that makes use of Session Initiation Protocol (SIP) trunks for PSTN connectivity can create greater potential for losses to toll fraud than traditional T1 TDM connectivity. For example, a compromised media gateway with two T1s could potential yield about 2,750 call minutes per hour for a fraudster to exploit. In contrast, a SIP trunk of roughly equivalent bandwidth and using a common compression algorithm could provide 6,000 call minutes per hour. So at a minimum, a SIP trunk provides at least double the amount of usage minutes to exploit, and perhaps several times more if bandwidth usage can be increased during off peak hours.

In the most basic scenario, a VoIP fraudster exploits a vulnerability to gain access to the IP-PBX or long-distance service, or both. There are four common configuration mistakes in VoIP and UC security architectures that can increase the risk of this type of exploitation:

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