Smartphone kill switches – a bad idea

A recent Star Tribune article noted that state and federal lawmakers are attempting to pass legislation mandating a “kill switch” for smartphones.  On the surface, this seems like a pretty good idea – after all, many of us are walking around with handheld devices worth hundreds of dollars, and those devices are a natural target for thieves.  If a customer can contact their service provider and get the device permanently shut down, the smartphone loses its value on the black market, deterring the theft in the first place.

But there’s a downside to this kill switch technology, which may not be obvious at first glance.  Some might call it a useful feature, but others see a bug which is more likely to impact users than the problem it solves.

Let’s remember that it’s only the idea of a kill-switch which is useful – the concept is to have it act as a deterrent.  The thief suddenly chooses not steal your phone because the market for stolen phones is depressed; customers are now able to contact their service provider and have that phone shut down.

Since technical details are still unclear at this early stage, it’s impossible to outline all the ways this concept is flawed.  But there are a few different scenarios which should be outlined in order to note how this kill switch would harm consumers.

The first is the most obvious – that this feature will be abused by law enforcement.  The kill switch will undoubtedly be asked to be activated against someone suspected of committing a crime, and possibly against those who have contacted a suspect.  Taking videos of a police officer is now an act that could revoke your cellular privileges.  Participating in a protest could also result in your phone being shut off since you could use it to communicate with others about where riot police are gathering – it’s for your own safety.

The second thing to remember is that the kill switch is permanent.  So when you’ve lost your phone and may have left it in a cab or between the couch cushions, once your phone has been disabled (which is a good idea if you have an sensitive data on your phone, such as access to your email), you’ll be buying a new one, which is exactly what the kill switch is supposed to prevent.  In the Marketplace article linked above, the subject mentions he’s had his phone stolen three times, and gotten it back twice.  Why bother getting it back if you’ve reported the theft and the carrier has had it rendered permanently inoperable?

There are those out there who think that carriers are refusing to install kill switches on their phones because they sell more phones this way, that phone thefts are a good way to keep reaching into their customers’ pockets.  A reminder about the players in this game is in order: carriers still essentially buy phones from manufacturers like HTC and Apple, and resell them at very little markup – the carriers still make a bulk of their profits through plans.  In fact, the addition of a kill switch to smartphones would negatively impact the used-phone market and force consumers to buy new devices – you really want to take a chance buying a used phone on ebay if it can be turned off at a moment’s notice or is already bricked?

Next, let’s look at another problem – shadowy hackers!  Anyone out there know how cheaply a fake cell tower can be constructed?  At DEFCON in 2010, it was about $1500.  And if you’ve seen more recent videos of people making these things, you know they’re cheaper and more effective now – there’s no way to stop your phone from connecting to them if properly created.  What happens when a fake cell tower transmits a kill signal to every phone that connects to it?  Some police departments already have these fake cell towers – they’re generically called “IMSI catchers” and one commercial model is called KingFish.

If kill switches are mandated by law, expect problems such as those listed above.  Worse yet, if these phones that have kill switches are ever able to be re-activated, thieves will figure it out, the deterrent effect is gone, and phone theft will continue.  Your phone will be almost the same as before, but now could be shut down at any time.

So how do we prevent smartphone theft?  Well, most of us carry objects worth hundreds or thousands of dollars every day – they’re called wallets.  They have IDs, credit cards, and cash in them.  Wallets are often secured in a similar manner to a cell phone – in a pocket or a purse.  But when I get on the bus to go to work, no one is mindlessly playing Candy Crush on their wallet.

I know legislators are well-intentioned, and they’re probably just trying to help.  And they always score points when they take on companies that are generally reviled, like phone companies.  But there are more important battles to fight than this one, and the idea of a  cellphone kill switch creates more problems than it solves.

2 thoughts on “Smartphone kill switches – a bad idea”

  1. Most of my wallet does essentially have a kill switch, though. I can render all my credit cards permanently inoperable with a few phone calls — and, in fact, I can do the same to other people (and have! my father once had his pocket picked while traveling internationally, and had me call his credit card companies because he couldn’t figure out how to get through to their 800-number from the Czech Republic.)

    And….although wallets are regularly stolen (since they frequently contain cash, as well) the prevalence of credit cards and the ease with which people can render them unusable almost certainly reduces the extent to which they’re targeted.

    On the other hand, I can get a replacement credit card at no charge, and I’m not going to be held responsible for any of the charges provided I attempt to notify my credit card company reasonably quickly. Replacing a bricked phone isn’t going to be a free transaction.

    If someone has sensitive data on their phone, they hopefully have installed an app that they can use to do a remote data wipe, if they’re worried; they could potentially give it a day or two and THEN brick the phone.

    1. Naomi – thanks for your comment, I appreciate it.

      Addressing your last statement first – if an adversary has your phone for even a day or two, you’re setting yourself up for trouble. Access to email means access to all the services connected to that email address (I’ll admit that working in information security sometimes makes me think like a criminal – that’s the best way to stop them, after all). Lots of people don’t even set pass codes on their phones, which to me provides greater peace of mind than the promise of a kill switch. The (admittedly lazy) point I was making about phones is that people are much less attentive with a phone than they are with a wallet because they provide a distraction – I think forcing handset manufacturers to address the fact that their customers don’t pay attention to their surroundings is misguided.

      I agree that wallets are targeted less frequently due to ease of credit card cancellation. Credit card info can still be targeted but is far easier to do in bulk and without the victim’s immediate knowledge. And yes, replacing credit cards is free, while replacing phones is expensive (unless you buy insurance from your carrier, which usually runs ~$10/mo).

      I think the heart of my argument against kill switches is that I find it implausible that my carrier can permanently brick my phone for any reason. And that “permanent brickification” seems to be what this suggestion of fewer thefts relies upon. I think this is an instance where politicians are thinking “Something Must Be Done; This Is Something; Therefore, This Must Be Done.”

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