Mobile Phone Flash Memory Chip Evidence

Mobile Phone Flash Memory Chip Evidence

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When recovering data using flasher box devices it may be useful to support the notion of obtaining a detail (IMSI/ICCID/etc) about a previously inserted paricular SIM Card in a particular mobile telephone that the notion about storing such data in memory is:

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- not new

- not clandestine shady black-box technology

- not a security breach by the handset manufacturer

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In fact the entire process of maintaining a SIM List in the phone was designed to allow a user with more than one SIM Card to gain access to previously held memory data associated with each particular SIM Card.

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In order to support that statement it would be helpful to see practitioners using authoratitive statements about the forensic 'reliability' and 'accuracy' of recovered data being obtained using flash reading devices and the evidential 'weight' and 'value' to be given to the data.

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To assist, here is a statement from a 1996 published Electronic User Guide for the Nokia 2110:

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SECURITY LEVEL (Menu 5 2) Page 71

"The phone keeps a list of the SIM cards which are used with the phone. This list may contain the information on up to five different SIM cards."

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However under the same section in the User Guide it states:

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"Regardless of the selected security level, all temporarily stored phone numbers are erased when a new SIM card is installed. On the other hand, these phone numbers are not erased when a previously used SIM card is inserted, regardless of the selected security level."

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As a query about forensic reliability and accuracy:

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- During the acquisition process and the harvesting of the data acquired is there/ has there been anything lost in translation of the data themselves, at first instance? If the IMSI you have recovered from flash memory is presented along with call logs etc, how do you know that those call logs relate to that IMSI and not another IMSI?

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As a query about evidential weight and value:

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- What weight can be given to the recovered IMSI being directly associated with those call logs? Moreover, what value is there in using such potentially uncorroborated evidence assigned to the recovered data being presented as evidence?

Looking back at the future of SIM in 2002

Looking back at the future of SIM in 2002

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I have always thought looking to the future is important, but equally looking back at what we know or think might be happening, from an historical perspective, can help see what problems can occur in the future and also to note whether foreseeable problems have been addressed or not, over time.

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I have selected a summary of issues discussed in training back in 2002, which are set out in the downloadable .pdf document "SIM - The Future as Viewed in 2002".

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http://www.filebucket.net/files/2537_89xfv/SIM%20The%20Future%20As%20Viewed%20in%202002.pdf

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For example, did you know or remember the slow down in SIM Card manufacturing in 2001? This is hard to believe when we think about the saturation levels of SIMs and handsets in the marketplace today.

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What about SIM Application Toolkits, applets and the exciting development of Java Standard Edition for mobile phones (KJava and PJava)? Our concerns then were how these advancements were going to impact on mobile telephone and SIM examination. Remember at that time we saw problems and tried to anticipate how to combat problems, but we had no immediate solutions which invariable had to be produced in some instance "on-the-hoof", so to speak.

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Cloning of SIM Cards had raised its head back in 1998 and devices were starting to appear on the market in 2000/01. The problems we faced then was knowing what to look for to deternmine whether a SIM was cloned or not? And then if the SIM was a clone what impact on evidence could/would it have?

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What about SIM Cards with multiple IMSIs? Still an issue today as it was then in 2002. The problem being is that SIM readers do not have the capability to read more than one IMSI from a SIM Card at any one time. Consequently, invocation of an IMSI selection in EF-7F20 6F07 is not possible other than the SIM being placed in the handset and another IMSI being selected using the handset menu Network selection. Moreover, once that has been done the green button on the handset needs to be pushed and a location update (and an IMSI-attach) to the network is required, which cannot be performed in a faraday bag, radio dampening field or isolation chamber. The question arises when do you search for more than one IMSI recorded into a SIM? What cases warrant it? How many cases have been missed in the past where more than one IMSI resided in SIM but has gone undetected? Put simply, when should allocution take place?

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There were a huge range of issues to be addressed then in early 2000, as there are now. When reading these brief discussion documents representing issues spoken about on my training courses, I hope they convey the message that plug and play (PnP) or universal plug and play (UPnP) systems used to extract and harvest data are simply not enough to satisfy the requirements for mobile telephone examination.