Entries Tagged "phones"

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Electronic Shackles and Telephone Communications

The article is in Hebrew, but the security story is funny in any language.

It’s about a prisoner who was forced to wear an electronic shackle to monitor that he did not violate his home arrest. The shackle is pretty simple: if the suspect leaves the defined detention area, the electronic shackle signals through the telephone line to the local police.

How do you defeat a system such as this? Just stop paying your phone bill and wait for the phone company to shut off service.

Posted on December 21, 2005 at 12:03 PMView Comments

Cell Phone Companies and Security

This is a fascinating story of cell phone fraud, security, economics, and externalities. Its moral is obvious, and demonstrates how economic considerations drive security decisions.

Susan Drummond was a customer of Rogers Wireless, a large Canadaian cell phone company. Her phone was cloned while she was on vacation, and she got a $12,237.60 phone bill (her typical bill was $75). Rogers maintains that there is nothing to be done, and that Drummond has to pay.

Like all cell phone companies, Rogers has automatic fraud detection systems that detect this kind of abnormal cell phone usage. They don’t turn the cell phones off, though, because they don’t want to annoy their customers.

Ms. Hopper [a manager in Roger’s security department] said terrorist groups had identified senior cellphone company officers as perfect targets, since the company was loath to shut off their phones for reasons that included inconvenience to busy executives and, of course, the public-relations debacle that would take place if word got out.

As long as Rogers can get others to pay for the fraud, this makes perfect sense. Shutting off a phone based on an automatic fraud-detection system costs the phone company in two ways: people inconvenienced by false alarms, and bad press. But the major cost of not shutting off a phone remains an externality: the customer pays for it.

In fact, there seems be some evidence that Rogers decides whether or not to shut off a suspecious phone based on the customer’s ability to pay:

Ms. Innes [a vice-president with Rogers Communications] said that Rogers has a policy of contacting consumers if fraud is suspected. In some cases, she admitted, phones are shut off automatically, but refused to say what criteria were used. (Ms. Drummond and Mr. Gefen believe that the company bases the decision on a customer’s creditworthiness. “If you have the financial history, they let the meter run,” Ms. Drummond said.) Ms. Drummond noted that she has a salary of more than $100,000, and a sterling credit history. “They knew something was wrong, but they thought they could get the money out of me. It’s ridiculous.”

Makes sense from Rogers’ point of view. High-paying customers are 1) more likely to pay, and 2) more damaging if pissed off in a false alarm. Again, economic considerations trump security.

Rogers is defending itself in court, and shows no signs of backing down:

In court filings, the company has made it clear that it intends to hold Ms. Drummond responsible for the calls made on her phone. “. . . the plaintiff is responsible for all calls made on her phone prior to the date of notification that her phone was stolen,” the company says. “The Plaintiff’s failure to mitigate deprived the Defendant of the opportunity to take any action to stop fraudulent calls prior to the 28th of August 2005.”

The solution here is obvious: Rogers should not be able to charge its customers for telephone calls they did not make. Ms. Drummond’s phone was cloned; there is no possible way she could notify Rogers of this before she saw calls she did not make on her bill. She is also completely powerless to affect the anti-cloning security in the Rogers phone system. To make her liable for the fraud is to ensure that the problem never gets fixed.

Rogers is the only party in a position to do something about the problem. The company can, and according to the article has, implemented automatic fraud-detection software.

Rogers customers will pay for the fraud in any case. If they are responsible for the loss, either they’ll take their chances and pay a lot only if they are the victims, or there’ll be some insurance scheme that spreads the cost over the entire customer base. If Rogers is responsible for the loss, then the customers will pay in the form of slightly higher prices. But only if Rogers is responsible for the loss will they implement security countermeasures to limit fraud.

And if they do that, everyone benefits.

There is a Slashdot thread on the topic.

Posted on December 19, 2005 at 1:10 PMView Comments

U.S. Compromises Canadian Privacy

A Canadian reporter was able to get phone records for the personal and professional accounts held by Canadian Privacy Commissioner Jennifer Stoddart through an American data broker, locatecell.com. The security concerns are obvious.

Canada has an exception in the privacy laws that allows newspapers to do this type of investigative reporting. My guess is that’s the only reason we haven’t seen an American reporter pull phone records on one of our government officials.

Posted on November 17, 2005 at 2:32 PMView Comments

Stride-Based Security

Can a cell phone detect if it is stolen by measuring the gait of the person carrying it?

Researchers at the VTT Technical Research Centre of Finland have developed a prototype of a cell phone that uses motion sensors to record a user’s walking pattern of movement, or gait. The device then periodically checks to see that it is still in the possession of its legitimate owner, by measuring the current stride and comparing it against that stored in its memory.

Clever, as long as you realize that there are going to be a lot of false alarms. This seems okay:

If the phone suspects it has fallen into the wrong hands, it will prompt the user for a password if they attempt to make calls or access its memory.

Posted on November 16, 2005 at 6:26 AMView Comments

SMS Denial-of-Service Attack

This is a clever piece of research. Turns out you can jam cell phones with SMS messages. Text messages are transmitted on the same channel that is used to set up voice calls, so if you flood the network with one, then the other can’t happen. The researchers believe that sending 165 text messages a second is enough to disrupt all the cell phones in Manhattan.

From the paper:

ABSTRACT: Cellular networks are a critical component of the economic and social infrastructures in which we live. In addition to voice services, these networks deliver alphanumeric text messages to the vast majority of wireless subscribers. To encourage the expansion of this new service, telecommunications companies offer connections between their networks and the Internet. The ramifications of such connections, however, have not been fully recognized. In this paper, we evaluate the security impact of the SMS interface on the availability of the cellular phone network. Specifically, we demonstrate the ability to deny voice service to cities the size of Washington D.C. and Manhattan with little more than a cable modem. Moreover, attacks targeting the entire United States are feasible with resources available to medium-sized zombie networks. This analysis begins with an exploration of the structure of cellular networks. We then characterize network behavior and explore a number of reconnaissance techniques aimed at effectively targeting attacks on these systems. We conclude by discussing countermeasures that mitigate or eliminate the threats introduced by these attacks.

There’s a New York Times article and a thread on Slashdot.

Posted on October 7, 2005 at 7:43 AMView Comments

Social Engineering Via Voicemail

Here’s a clever social engineering attack:

The Division has received a number of calls concerning a voicemail message left by an anonymous female caller urging them to purchase a particular penny stock. The message is intended to appear as if the caller is calling a close friend and has dialed the wrong number. The caller talks fast stating she has a great inside deal on a penny stock. The caller personalizes the conversation by saying the recommendation comes from a broker the woman is dating and that her father previously purchased stock and made a huge profit. The purpose of the call is to make you think you’ve received a hot stock tip by mistake.

Posted on May 20, 2005 at 8:37 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.