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Jamming Cellphones with Text Messages
Steve writes "Some Penn State professors and students have published a way to jam cellular voice service with simple text messages. From the article: 'Because text messages are transmitted on the same signal that is used to set up voice calls, just 165 messages a second is enough to disrupt all cellphones in Manhattan.' Cellular providers, of course, fired back, one stating that it 'constantly and aggressively monitors potential threats to the integrity and security of its network.'"
165 messages a second would cost you about ten thousand dollars a minute, at the prices the cell companies charge.
Note to mods: I'm probably being sarcastic.
more like!
Engineering is the art of compromise.
A more detailed description of the threat is at smsanalysis.org/. The actual paper at smsanalysis.org/smsanalysis.pdf.
Don't you think that there are already more than 165 text messages being sent out every second in Manhattan?
Easy enough, about 3 or 4 japanese school girls should be able to send a sustained rate of 180 messages a second.
I'M NOT ANGRY!
Most people don't know that you can send text messages for free through Google's text messaging service.
... hello? ...hello?
http://toolbar.google.com/send/sms/index.php
Now all you need is a perl script and
-------------
judge a man by his wallet
------ The best brain training is now totally free : )
The reason for this prioritisation is that delaying isochronous (eg. voice) data makes it unusable, but backing up text is OK. If you try jamming with text all you'll end up with is a load of backed up text.
Engineering is the art of compromise.
You could send 165 text messages a second OR you could keep calling the phone you want to disrupt!
Except this isn't about disrupting one phone - this is about disrupting the entire regional network. Just the sort thing a criminal or terrorist might want to do during or in the wake of some mal-behavior. So it costs a bunch to send those messages? So what? Bad guys can have some real (or fraudulant) financial resources when that's part of their plan.
Don't disappoint your bird dog. Go to the range.
Last year I had a friend that wrote an app that would text message a verse from the 12 days of Christmas every day, but something went horribly wrong and I was getting messaged a verse from that damn song every few milliseconds for a couple hours straight. Not fun.
Hey Steve! (you ass)
Do you have a source?
So it costs a bunch to send those messages? So what? Bad guys can have some real (or fraudulant) financial resources when that's part of their plan.
...
1) Sign cell phone contract with monthly billing.
2) Send massive amounts of text messages.
3) Blow self up.
4) Don't care if phone bill is high at end of month - having too much fun with the 72 virgins.
5)
6) Profit?
Yeah, but lets face it. There are so much better things to do with 3 or 4 japanese school girls than text messages.
The laws of probability forbid it!
If you think 2 to 4 simultaneous telephone calls will take down a cellular network, the thing would have stopped working a long time ago.
But... I think it's not the vox bandwidth - it's that part of the system that manages the call overhead (per the summary, the part of the system that "sets up" the calls). I believe that housekeeping does indeed take place in a smaller, and separate piece of the spectrum and the network's plumbing. Of course, IANATE (I am not a telecommunications engineer). Text messaging piggy-backs on the data that keeps the system and the phones aware of each other - long before a call (and the related bandwidth) is actually assigned to an user that dials/answers. This would be when someone who works for Verizon or Spring would anonymously chime. We can hear you now, good.
Don't disappoint your bird dog. Go to the range.
You can email a text message to someone's phone, and for some carriers it is an automatic $0.10 or more a message received and the reciever can't not recieve it. Here are all the SMS addys:
Sprint: 10-digit-number@messaging.sprintpcs.com
Verizon: 10-digit-nmber@vtext.com
AT&T: 10-digit-number@mobile.att.net
T Mobile: 10-digit-number@tmomail.net
Nextel: 10-digit-number@messaging.nextel.com
Cingular: 10-digit-number@mobile.mycingular.net
Alltel: 10-digit-number@message.alltel.com
i can see how they could put in safe-guards like monitoring multiple messages from an IP in a certain time frame. but, smart programmers can work around this fairly easily.
Several years ago I was involved in solving a similiar problem in the GSM/MAP/SS7 backbone network of a major European cellular provider/broker. In that case, there was an problem because the SMS messaging is carried in the MAP "signalling" layer, which resulted in the waste of the vast majority of the bandwidth that was meant to be used to handle subscriber management, roaming, authentication, etc. The network (which provided roaming between 100+ sizable European, Asian, and North African carriers) was being saturated with internet-generated SMS text messaging. Essentially, we were only able to block the traffic, having little control over its generation and/or entry into the network.
Clearly the people that designed the air interface made the same poor architectural decision.
For those of you who have never looked at a real phone network, allow me some bandwidth:
Nobody has ever allowed for a one to one switching network like you may have seen with a switched hub. It's too expensive. They use trunk lines instead. The number of trunk lines depends on the statistics of the local area calling. There are benchmarks to use for various types of service. These systems are designed for four and five nines of up time. But it's not overload proof. You have all gotten fast busy signals before. That's because there were no trunks available.
What these folks have figured out is how much bandwidth a typical cell site can have. They have figured out how many text messages it would take to fill up that available bandwidth. Big Deal. Cell sites do saturate. This is not a design "flaw" --it's a design point. Just as almost nobody builds buildings to withstand 200 MPH winds, almost nobody builds that much bandwidth in to a cell site. You could, but it would almost never get used.
Instead we build them to handle almost all conditions. Yes, they can saturate. That's a political design issue. Someone who knows the design points can certainly overload one. But during normal use, they will work just fine. Since there are no lasting effects from such overload, most engineers figure that people will just clear out before things get too dicey.
Naturally, some twits who want to jam cell phone conversations will find plenty of ways to do this. The network is built for civil use --not military use. That's why police and fire authorities use seperate communications networks (or if they don't they're just asking for trouble). That's why ham radio operators are often able to render assistance when everyone else is busy trying to call home. Common Carrier networks will overload at some point, just as roads can saturate and slow to a crawl. We'll never have enough bandwidth or enough roads. But we can ensure that there will be enough to get by.
The Times could do for a brief lesson in engineering design criteria...
Nearly fifty percent of all graduates come from the bottom half of the class!