Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Battery power alone can be used to track Android phones

bbc.co.uk

Post reply on HN
Print view View original

21–30 of 78 posts

Re: Battery power alone can be used to track Android phones

#21

Post by Jolijn »

PJDK wrote: post #8

This is really selling a quite interesting intellectual effort on meaningless paranoia. Who would have any interest in tracking people in this manner? Any government based group can grab the data much more conveniently via the phone towers. Anyone else? Well you've got to trick someone into downloading this thing, so it's probably not that good for targeting a specific individual. If you can think up some nefarious s…

Technology is not exactly known to be stagnant. What is not practical now could be in just a few years.

For high value targets, all bets are off anyway. Some nation states have virtually unlimited resources they can call on.

Re: Battery power alone can be used to track Android phones

#22

Post by PJDK »

Jolijn wrote: post #21
PJDK wrote: post #8

This is really selling a quite interesting intellectual effort on meaningless paranoia. Who would have any interest in tracking people in this manner? Any government based group can grab the data much more conveniently via the phone towers. Anyone else? Well you've got to trick someone into downloading this thing, so it's probably not that good for targeting a specific individual. If you can think up some nefarious s…

Technology is not exactly known to be stagnant. What is not practical now could be in just a few years. For high value targets, all bets are off anyway. Some nation states have virtually unlimited resources they can call on.

Yeah, exactly. This is just a back door to phone tower triangulation, something every nation state has access to and uses regularly and publicly as part of normal criminal investigations.

Re: Battery power alone can be used to track Android phones

#23

Post by S_A_P »

Maybe I am a bit dense here, but how does battery drain map to a location? What would they be cross referencing to gather location?

All I can gather is that they would also need to know what tower you were talking to, and then based on the drain they could probably guess where you were based on some heuristic. Meaning, if you are talking to tower x, and the battery drain is high, you could guess that you are either far from the tower or indoors somewhere. It still seems to me that this is dubious at best. I get that technology is always changing, but wouldn't it just be easier to exploit a security hole?

Re: Battery power alone can be used to track Android phones

#24

Post by ttty »

jahnu wrote: post #13
ttty wrote: post #9

Earlier quoted context omitted.

But that if the battery discharges exactly the same. I think that is not the case, for example the battery when is at 50% might discharge (doing the exact thing) differently than when is at 20%. Maybe the battery is not well calibrated or the internal part of the battery are more wasted than others.

I would guess that even if the curve is different from say 50% to 40% than 20% to 10% for the same journey it would be easy enough to normalise the data after profiling a couple of phones.

Plus continuous change, but not even, would not be that easy.

Re: Battery power alone can be used to track Android phones

#25

Post by wongarsu »

S_A_P wrote: post #23

Maybe I am a bit dense here, but how does battery drain map to a location? What would they be cross referencing to gather location? All I can gather is that they would also need to know what tower you were talking to, and then based on the drain they could probably guess where you were based on some heuristic. Meaning, if you are talking to tower x, and the battery drain is high, you could guess that you are either f…

As you move, your distance to the closest cell tower changes. You also move past signal obstacles, so the change in signal strength isn't linear. They claim that these changes are characteristic enough that you can track movement that way.

Re: Battery power alone can be used to track Android phones

#26

Post by S_A_P »

wongarsu wrote: post #25
S_A_P wrote: post #23

Maybe I am a bit dense here, but how does battery drain map to a location? What would they be cross referencing to gather location? All I can gather is that they would also need to know what tower you were talking to, and then based on the drain they could probably guess where you were based on some heuristic. Meaning, if you are talking to tower x, and the battery drain is high, you could guess that you are either f…

As you move, your distance to the closest cell tower changes. You also move past signal obstacles, so the change in signal strength isn't linear. They claim that these changes are characteristic enough that you can track movement that way.

I get that part and to some degree understand. Maybe I am misinterpreting the "track your location" as something more accurate than "this person is in a 10 mile radius of this tower". For instance, wouldn't you need to know details of how different buildings are constructed? If you are in a busy downtown area, tracking with this method seems impossible. I could see if it was a remote area with few buildings to sift through.

Re: Battery power alone can be used to track Android phones

#27

Post by wongarsu »

zipperhead wrote: post #19
leereeves wrote: post #10

Earlier quoted context omitted.

The typical consumer would probably just give the app access to the GPS. The hard part is getting them to download it. Interesting research but not the most practical attack.

That's the problem with android. The 'typical user' has no control over individual app permission - it's literally all or none. If you install the app you give it access to the GPS, as long as it has specified that permission.

Rooted Cyanogenmod actually has privacy settings which enable you to restrict some permissions on a per-app basis. For example I don't allow Facebook Messenger access to GPS and Android asks me before Messenger gets camera access.

Re: Battery power alone can be used to track Android phones

#28

Post by wongarsu »

S_A_P wrote: post #26
wongarsu wrote: post #25

Earlier quoted context omitted.

As you move, your distance to the closest cell tower changes. You also move past signal obstacles, so the change in signal strength isn't linear. They claim that these changes are characteristic enough that you can track movement that way.

I get that part and to some degree understand. Maybe I am misinterpreting the "track your location" as something more accurate than "this person is in a 10 mile radius of this tower". For instance, wouldn't you need to know details of how different buildings are constructed? If you are in a busy downtown area, tracking with this method seems impossible. I could see if it was a remote area with few buildings to sift t…

Yes, it's not as trivial as just grabbing the data and running a generic algorithm. Ideally you would want to measure all routes where you want to track people. Kind of like how google knows where every wifi access point is and uses that for location information.

Also, you need people to move. Because you only have power data, you only know the aproximate signal strength if the person isn't moving.

Re: Battery power alone can be used to track Android phones

#30

Post by IanCal »

S_A_P wrote: post #26
wongarsu wrote: post #25

Earlier quoted context omitted.

As you move, your distance to the closest cell tower changes. You also move past signal obstacles, so the change in signal strength isn't linear. They claim that these changes are characteristic enough that you can track movement that way.

I get that part and to some degree understand. Maybe I am misinterpreting the "track your location" as something more accurate than "this person is in a 10 mile radius of this tower". For instance, wouldn't you need to know details of how different buildings are constructed? If you are in a busy downtown area, tracking with this method seems impossible. I could see if it was a remote area with few buildings to sift t…

> For instance, wouldn't you need to know details of how different buildings are constructed?

They learned the typical profiles of power use for different journeys and then tried to distinguish between them (at least in one experiment).

http://arxiv.org/pdf/1502.03182v1.pdf

Post reply on HN