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RF shielding

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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Re: RF shielding

Post Posted: Tue Jan 29, 2013 2:11 am

- Horking
- taurean25
All,

Does anyone know of any RF shielding solutions that provide battery power to keep the acquired mobile device powered?

There maybe situations where if the device looses power, it may not be possible to gain access to the device again due to encryption or difficult passcodes.


The cellphone battery lose energy very quickly when RF shielding,because searching signal never stop.so u can use the Shielding bag with the external battery by USB port:)





There is also the point to make, apart from whether the mobile is going to die on its feet due to loss of battery charge or the battery charge is sustained, whether the RF and network attach state is of equal importance, particularly regarding the OP original point about receiving SMS.

Being able to explaining the RF and network attach state can assist evidentially as to the value and weight to be given to the events as set out by the OP.

At some stage confirmation as to what is happening and can be seen on the screen with the handset that is switched on and contained within a RF dampening field container/chamber may assist a particular issue.

How often do you see a report containing a statement, and maybe with a photo, that in the dampening field:

- the mobile had 'no coverage' as depicted by the symbols on the screen
- the mobile phone went into emergency calls only mode
- the screen was blank other than mobile screen mode




When considering these issues the standards do provide useful observations about the RF and network attach state. I have used one example from a GSM/ETSI TS for 1999 to illustrate that nothing I am saying is new, it has always been there Using the standards to help define the technical level of the issue raised by the OP may assist.

For instance absolutely no RF signal and no attach state may possible produce a statement relevant to 'nothing got through'. In the emergency calls state an attach state may occur but the likelihood that the emergency calls channel would be used to send commercial or private SMS text messages would appear unlikely. However, the OP identified receipt of an SMS, but it is not clear whether this came form the subscriber home network or delivered by a roaming network or third party proxy manager. It does confirm however that technically the subscriber was attached to a network, but what we do not know at this stage is whether the mobile was able to send an acknowledgement that the text message was received or whether the network would continue to transmit the SMS at interval for the suration of the 'delivery period' requirements.

Studying and understsanding the locale in which the container was present at the time of the unwanted SMS intrusion and noticing the density of masts/tower and the transmission technology/ies around it (the container) may assist investigate how the SMS message made it through the dampening field, can be included as part of the investigation and reported as necessary.
_________________
Institute for Digital Forensics (IDF) - LinkedIn
Mobile Telephone Examination Board (MTEB) - LinkedIn
Mobile Telephone Evidence & Forensics trewmte.blogspot.com
ForensicMobex now MTEB Linkedin Subgroup 

trewmte
Senior Member
 
 
  

Re: RF shielding

Post Posted: Tue Jan 29, 2013 7:54 am

if money isn't a problem have a look at the new mobile faraday cage of the forensic institute in The Netherlands.
www.forensicinstitute....aday_cage/  

kbertens
Senior Member
 
 
  

Re: RF shielding

Post Posted: Tue Jan 29, 2013 8:55 am

- rjudy55
Here's a nice breakdown with some indicators of signal to db. http://powerfulsignal.com/cell-signal-strength.aspx.

Yes and no.
Meaning yes Smile , it is a nice generic explanation , but no Sad , it is too generic to be of any practical use .

I know how it is easy to fall in the two extremes of "too generic/simple/simplified and thus unuseful" or "too technical/difficult and thus unuseful as well", what I find is needed is often the actual "meanigful" data (that only the technical/difficult version contains) but simplified into "layman's term" as much as possible.

If you want a quick laugh, check this:
www.msfn.org/board/top...net-noise/
where I hopefully solved the issue about "How much is 300 g?"

jaclaz
_________________
- In theory there is no difference between theory and practice, but in practice there is. - 

jaclaz
Senior Member
 
 
  

Re: RF shielding

Post Posted: Fri Feb 01, 2013 1:34 am

- kbertens
if money isn't a problem have a look at the new mobile faraday cage of the forensic institute in The Netherlands.
www.forensicinstitute....aday_cage/


Nice looking piece of kit. This may seem like an injustice to NFI's marketing blurb, and apologies in advance for any hurt feelings, but the kit doesn't look easily portable.

I read the leader information on the webpage link you gave and it states (below), generally speaking, nothing gets in with respect to EM signals. And (shouldn't really start a sentence with an 'And') NFI has a high reputation and it is expected that NFI will work to high standards anyway. I just wondered though, do you know whether NFI conducted an analysis of what is happening with the device and its internal activity onced locked inside and switched ON inside the Faraday container and what their analysis found?

- Netherlands Forensic Institute
No electromagnetic signals

A Faraday cage is a container made of a conducting material that filters out electromagnetic signals. A mobile phone placed inside the cage therefore cannot receive calls or be wiped remotely. Investigators using the cage's special conductive gloves can put their hands in the cage, to retrieve and secure the most important data immediately. They can see what they are doing on a monitor./



The other statement I noted was:

- Netherlands Forensic Institute
Improvements

The NFI has examined the weaknesses of existing Faraday cages and developed a new model in collaboration with police forensic investigators.


So when they say 'weaknesses of existing Faraday cages' is that confirmation they mean Faraday containers on the market, generally, and, if so, do they have the research we can read please as to which ones they have found to be shown to have weaknesses?
_________________
Institute for Digital Forensics (IDF) - LinkedIn
Mobile Telephone Examination Board (MTEB) - LinkedIn
Mobile Telephone Evidence & Forensics trewmte.blogspot.com
ForensicMobex now MTEB Linkedin Subgroup 

trewmte
Senior Member
 
 
  

Re: RF shielding

Post Posted: Sat Feb 02, 2013 4:11 am

- jaclaz
what I find is needed is often the actual "meanigful" data (that only the technical/difficult version contains) but simplified into "layman's term" as much as possible.


So we need to present together technical meaningful information and non-technical meaningful information so that when shown the layperson can follow it:


If you want to see the full image above (for windows users) right click the mouse and select 'view image'. For MAC users just push any key and something happens without an OOM, errr...wont it!?!

ps - Jamie is there a way we can show images at site that are not half obliterated by the additional forum bar at the side without having to resize an image to load at FF (as this can distort features in the image) please?
_________________
Institute for Digital Forensics (IDF) - LinkedIn
Mobile Telephone Examination Board (MTEB) - LinkedIn
Mobile Telephone Evidence & Forensics trewmte.blogspot.com
ForensicMobex now MTEB Linkedin Subgroup 

trewmte
Senior Member
 
 
  

Re: RF shielding

Post Posted: Sat Feb 02, 2013 1:06 pm

- trewmte

So we need to present together technical meaningful information and non-technical meaningful information so that when shown the layperson can follow it:

I am clearly failing to see your point. Question

Unless I am mistaken a not-so-little part of the members had the false impression that these carrying bags were something akin to a write blocker, something "binary", on/off or black/white.

What came from the mentioned sources is that they are instead a sort of "muffler" for signals/radio frequencies.

This means that the final user might be convinced that he/she is using a "totally safe" protection whilst in reality there may be cases when signals "go through" and can somehow modify the evidence handy.

It would be logical to provide "real life examples" of when this may happen, knowing that not everyone - though being an excellent digital forensic examiner or LE officer - might have a specific knowledge on cellular networks, signals, etc. (particularly since - from what I get from the board posts - there is a tendency to have evidence collection and delivery to the laboratory a separate step, often performed by other people, from the actual analysis of the device).
I.e. it seems to me like the mere "collection and delivery" is often carried out by people that might have only the specific training/knowledge for these steps, and possibly lack the higher degree of instruction on cellular networks that the actual forensic expert might have.

Of course it is very possible that I am the only one that has difficulties in "digesting" db attenuation of signals and actual minimum "safe" levels and all the rest Embarassed , in which case I will gladly "downgrade" the question about these thingies from a "useful to the community" question to a "jaclaz's personal" question.

jaclaz
_________________
- In theory there is no difference between theory and practice, but in practice there is. - 

jaclaz
Senior Member
 
 
  

Re: RF shielding

Post Posted: Sat Feb 02, 2013 4:49 pm

- jaclaz
- trewmte

So we need to present together technical meaningful information and non-technical meaningful information so that when shown the layperson can follow it:

I am clearly failing to see your point. Question


jaclaz it is not you, but me. I thought I understood your humour and thought you would see the funny side of the diagram. I was laughing with you, and most certainly not at you. Apologies for the misunderstanding.

Maybe with a fresh understanding of what I am doing with the diagram you can laugh with me.

For the record I am not disputing what you were saying. best regards.
_________________
Institute for Digital Forensics (IDF) - LinkedIn
Mobile Telephone Examination Board (MTEB) - LinkedIn
Mobile Telephone Evidence & Forensics trewmte.blogspot.com
ForensicMobex now MTEB Linkedin Subgroup 

trewmte
Senior Member
 
 
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