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iPhone in-river location concept

Discussion of forensic issues related to all types of mobile phones and underlying technologies (GSM, GPRS, UMTS/3G, HSDPA, LTE, Bluetooth etc.)
Subforums: Mobile Telephone Case Law
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iPhone in-river location concept

Post Posted: Fri Jan 13, 2017 1:04 am

In a murder case we had to find an iPhone 5s which was thrown to avoid collection into a river. At the time of throwing the iPhone was switched on and Find My iPhone (FMi) activated. The river had a low level of water depth about 1m but bad optical contrast as black case and river ground almost dark.

By calling the iPhone it responded by being reacheable and functional to ring. This proves that cell tower reception was duplex running. FMi is based on cell towers, WiFis and GPS - all just as available at the time. So accuracy of location of FMi is in worst case 10-20 square meters wrong. Our divers got the device successfully, but

How could the weak signal (paging) of the iPhone underwater be detected without divers?

We try to build a swimming construct with own GPS and RC-controlled strong lamps and vertical underwater-cam with real-time video transmission to land. What we are unsure is how to design and build a sensor head to locate the signalling of the iPhone. The process to find the device is very time-sensitive as battery will run out and may water damage will make the device non-responsive.

Have you a solution running for this in your corps? Any other good idea?

We want to learn from the Best - You!

Thank you.  

Last edited by RolfGutmann on Sun Jan 29, 2017 5:15 pm; edited 1 time in total

RolfGutmann
Senior Member
 
 
  

Re: iPhone in-river location detection

Post Posted: Fri Jan 13, 2017 12:26 pm

If you are running a goverment or justice research, use trilateration of Mobile cells which gives you a very precise location similar to GPS (10 meters aprox).

Depending on which country are you located, i could provide you location by phone number using trilateration on SS7 worldwide. (only for goverments and if country is under coverage)

Any underwater RF finder will do the trick as you could see the connection to tower.  

droopy
Senior Member
 
 
  

Re: iPhone in-river location detection

Post Posted: Fri Jan 13, 2017 1:33 pm

Thank you droopy for your offer.

I am in action for Law Enforcement, Gov.

To locate a cell phone by SS7 I was aware, but how does this fit into the core network in-country running on Diameter and Attribute Value Pairs AVPs? As a cell phone can be connected by Mobile Broadband Network, WiFi or DSL (WiFi interworking) or even DSL-LTE Bonding where does the SS7 reachability actually ends?

As small and macro cells evolve with operator's public WiFi Access Points AP a solution based on IP could be the most accurate solution to come close to the location and the Tracking Area Code TAC (LTE) or Location Area code LAC (UMTS)?

As you are an expert please help me to better understand the solution after 'AnyTime Interrogation ATI'.

Please help me.

Update: We test underwater RF Signal propagation in that river to replay the situation a few days ago.  

RolfGutmann
Senior Member
 
 
  

Re: iPhone in-river location detection

Post Posted: Fri Jan 13, 2017 6:10 pm

You could use VLR location to interrogate a mobile.
SS7 has this feature carrier to carrier under agreements.
We have access as goverment to it for location. Depends on which country and carrier you have.

We use trilateration and have less than 10 meters accuracy which is same or better than GPS.
It is mainly use for terrorist tracking but it could be use under an official request.

Even you could trace back from Apple servers the findmyiphone previous locations tracks and historical data for many weeks or years. But legal authorization is required.

Techinically, you could always locate a mobile in the world.  

droopy
Senior Member
 
 
  

Re: iPhone in-river location detection

Post Posted: Fri Jan 13, 2017 11:56 pm

- RolfGutmann

Update: We test underwater RF Signal propagation in that river to replay the situation a few days ago.


The propagation loss for a 800 MHz signal in 1 m freshwater is around 30 db, and around 70 db at 1700 MHz. It's not worth the effort, I think. However, it could be an advantage and lead to some results when using active GSM equipment, that the handset is probably pushed to GSM just by the environmental RF shielding (at least if registered for a low-band network).  

C.R.S.
Senior Member
 
 
  

Re: iPhone in-river location detection

Post Posted: Sat Jan 14, 2017 3:59 am

Rolf, are these any help to you:

Electromagnetic Wave Propagation into Fresh Water
file.scirp.org/pdf/JEM...390291.pdf

RF Path and Absorption Loss Estimation for Underwater Wireless Sensor Networks in
Different Water Environments
www.ncbi.nlm.nih.gov/p...-00890.pdf
_________________
Institute for Digital Forensics (IDF) - www.linkedin.com/groups/2436720
Mobile Telephone Examination Board (MTEB) - www.linkedin.com/groups/141739
Universal Network Investigations - www.linkedin.com/groups/13536130
Mobile Telephone Evidence & Forensics trewmte.blogspot.com 

trewmte
Senior Member
 
 
  

Re: iPhone in-river location detection

Post Posted: Mon Jan 16, 2017 6:28 pm

@droopy, first thank you! After Carsten Nohl (srlabs) revealed the SS7 attack many operators closed the ATI command. Focussing on the VLR is a good approach. #Find My iPhone location request in certain cases is too slow and I fear to get no more RF signal from the device. But will test.

@C.R.S. Thank you for RF signal path attenuation values, deducted from av. values of -70 - -100 dBm I guess at about 2 meters the end comes for the overwater approach. Dropping 3 sensors to measure unterwater requires a fine-tuned upriver approach to get close to the device (to avoid durt swirling up). This ground-based approach seems impossible, but never give up. To drop e.g. M-TMSI-catching (LTE) sensors would push the device to power-up his RF signal. But the serial/sequential round-robin approach 1-2-3 has to be timely delayed between to not confuse the device. Seems costly.

@trewmte Thank you!  

RolfGutmann
Senior Member
 
 

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