Friday, May 15, 2009

Undercover Officer Down, how might SIM Access Control Class help? Part 1

PART 1: Undercover Officer Down, how might SIM Access Control Class help?
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The following is a scenario created to help examiners and experts know more about how to determine what data in SIM/USIM elementary files can mean and to appreciate what is required to be understood before examining SIM/USIM and giving evidence. Computer forensics has made a significant contribution to data recovery that can be used for harvesting data from mobile telephones and SIM cards, however data recovery is only one element of mobile telephone evidence and is not ‘the evidence’ to be considered in isolation to everything else.
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Moreover, an examiner and an expert are expected to usefully advise with respect to investigations where data obtained from mobile telephones and SIMs/USIMs are involved, so, here to, this scenario will hopefully open examiners' and experts' eyes to new ways of considering data. What the law of evidence wants to know is, provided the data recovered is not a problem, what does the data actually mean and how should it be interpreted.
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Scenario
An undercover officer working has infiltrated a criminal organisation involved in drugs and people trafficking. The undercover officer needs to keep details and seek answers without blowing his cover. The situation is always life threatening. The officer is required to report back by mobile phone to Control every 7-14 days.
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PC0001 on patrol in the Shopping Mall sees a known drug dealer in the doorway of a Supermarket with an unknown IC1 female handing over a package. PC0001 calls and waits for back up before approaching. A stop and search is then conducted using the appropriate procedures under PACE 1984. A quantity of drugs is found, large bundle of money, along with two mobile telephones which were all subsequently put into evidential containers and the two individuals are carted off in the wagon to the local nick.
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The alleged crime of drug selling (given the quantity seized) is fairly low down the scale and the money found was £1,780.00, but compared with other crimes wasn’t high and so priority won’t be given to this case over other cases in the system. The mobile phones are sent away for examination. The person assigned to deal with the examination of the mobile telephone and SIM card conducts a quick level examination for subscriber details, mobile telephone number, SIM serial number/ICCID, phonebook and text messages. Before starting examining the mobile telephone the examiner becomes ill and doesn’t complete the work.
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The examination would need to be passed to another examiner who would have to start from scratch as the next examiner could not possibly give evidence about someone else’s work for the new examiner would have no knowledge about the previous examination. By chance the new examiner chosen for the work had just come back from Greg Smith’s TrewMTE SIM Card training course where he had undergone deep level training into being a professional examiner and taught about ethical working practices, understanding the symbiotic relation with other mobile telephone devices and network elements, technical standards, working practices and SIM Card examination and data investigation etc (well alright, but it is only a modest promotion about me).
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The new examiner conducted a fresh examination, starting with the SIM Card. Having been trained to look for evidence of activity and indicators about the potential user of the SIM card, the new examiner immediately contacted the Senior Officer where PC0001 was stationed. The new examiner, having been trained to identify certain data and corroborate the finding with reference material to ensure the meaning of the data, explained to the Senior Officer that he was examining a mobile telephone SIM Card that may belong to someone in the Security Services and that if he, at the local level, was examining this SIM then it could mean there was a man [undercover] down in the field?
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Asked why the new examiner might suspect this, he referred to the recent training he had had and had identified from a mandatory data file in the SIM Card an elementary file titled EFACC (Access Control Class). The SIM had recorded Access Class 12 which is referenced as “Security Services”. The examiner also informed the Senior Officer that he had acquired from the SIM the subscriber details and mobile telephone number but was not authorised to access personal details. The examiner also mentioned that as ex-British Army he had field experience and should “intel” suggest there may be a “man down” that he would rely on all efforts to be made to rescue him, he therefore considered the user of the SIM (being examined) would equally rely on the same.
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The Senior Officer took the details and immediately set in motion a priority search. The details the new examiner had given to the Senior Officer had proven correct and were linked to an officer on field ops. It transpired the office had not been in contact for 14 days. Because of the work involved MI5 were called in for their superior network of intelligence and, given the nature of the criminal organisation, every school boys heroes were sent in, the SAS, to conduct ground surveillance, attack, capture and rescue. The undercover officer was rescued, badly beaten, bleeding and barely alive, but alive nonetheless.
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To clear up some loose ends to this scenario: How did the drug dealer come to be in possession of the undercover officer's mobile phone? The undercover officer had been rumbled by the gang and when running away, before the gang captured him, he had thrown it away and working on the long shot he hoped that someone would find it and hand it in. The drug dealer had found it, assumed it had been dropped by a passer-by and considered it could provide anonymity for drug dealing. There is a separate story about other evidence the mobile tied to the drug dealer, but this scenario is about saving an important life.
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So what can be learned from the above scenario and what facts are known:
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a) that the examiner as fact needs proper training to know what data can be significant
b) that as a statement of fact there is an elementary file in SIM called EFACC (Access Control Class)
c) that as a statement of fact the elementary file EFACC (Access Control Class) can be assigned to a User with an Access Class 12 assigned to “Security Services”
d) the examiner should know the limitations of the tools s/he works with before using them
e) the examiner to have the tools that actually reveal the information that is significant
f) that a proper and full examination of a SIM is an absolute requirement rather than merely the examiner conducting a dumbed-down check, only looking at certain data sets
g) that checking the findings immediately following a SIM read is essential
h) to communicate straightaway of the potential for life threatening situations or national security
i) that “priority” check means “speed and instantly” and not manyarna
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In part 2 it will identify the full 16 Access Classes, look at Class 12 technical elements for Access Control Class, how it works, its uses and its limitations. What will become abundantly clear, if Part 1 and Part 2 are only dealing with Access Class 12 what can be learned about all the other Access Classes? More importantly, why has proper checking about Access Control Class and other EFs in SIM Cards not become standard practice?

Thursday, May 14, 2009

Mobile Telephone Examination Procedure

Mobile Telephone Examination Procedure
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This discussion continues on the theme to highlight, over the last five years, the diminishing quality of the knowledge in mobile telephone evidence training and very poor understanding by those giving advice about or presenting mobile telephone forensic evidence and opinion.
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By way of further illustration about poor understanding which was given in an advice note regarding mobile telephone examination procedure, the advice given:
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(1) by removing the battery of certain make/model of mobile telephone can lose the date and time stamp and call history, but using a Shielding Room can prevent this because you won’t need to remove the battery.
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(1a) the party giving the advice above then went on to suggest they did not think, by and large, the above is a better methodology that should be adopted and went on to advocate that the method of producing a clone test SIM (Access Card) appeared to them to be more appropriate.
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A shielding room is used to prevent radio signals entering a given space that the shielding is designed to protect, and also prevent the mobile telephone from registering to the mobile telephone network; [it] cannot though prevent loss of full call history and date and time stamp irrespective of whether the mobile telephone is in a shielded room or not. Removing the battery on some older models of mobile telephone can lose the full call history and date and time stamp. To produce a clone test SIM (Access Card) the examiner is required at first instance to remove the battery to get to the SIM/USIM. So how is their recommendation shown (in 1a) that it is any better than the unsuitable Shielding Room scenario (in 1)?

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- For the record the point I am making is not to advocate shielding rooms or faraday bags, I am just pointing out the absurdity of the advice -
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By noting in their advice that using a Shielding Room may not be the best method (thus tacitly negativing its use) the advice then goes on to positively suggest that the examiner wouldn’t need to remove the battery because it is in a shielding room and that call history and date and time stamp on the mobile telephone would be secure. They then go on to advocate the removal of the battery which implicitly requires taking the SIM out also from the handset for the purposes of producing a clone test SIM (Access Card). Their advice is confusing as they have already admitted removing the battery can lose data.
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An examiner will naturally have to remove the SIM/USIM out of the handset anyway (thus removing the battery first is one point; another point being removing the SIM/USIM can inevitably cause loss of data in the handset - it can't be helped) because the proper order of examination requires a full examination of the SIM/USIM to get at evidence that is not readily available and obtainable by leaving the SIM/USIM in the handset during examination.
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I concluded from reading their advice that it contained so many mixed messages and conflicting use of methodologies which each method that would usually be used for the treatment of different issues in isolation were now being squeezed together to make them work, would leave an examiner following their advice open to and vulnerable to potentially discrediting their own evidence.

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Moreover, if the advice note was intended to succeed in getting an examiner to use Access Cards over Shielding Rooms then in my view it failed to convince me to use one or not the other.

Monday, February 02, 2009

SIM PIN Challenge 2

SIM PIN Challenge 2
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A reminder that this challenge ends on the 15th February 2009:
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http://trewmte.blogspot.com/2009/01/sim-pin-challenge.html
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No pressure here guys, but we have had the first written response to the SIM PIN Challenge from a Challenge Entrant who has just started in mobile telephone forensics. This Challenge should therefore be a walk in the park for all you mobile phone and computer forensic examiners who have given evidence about SIM Cards in Court.
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As a brief history about SIM Cards, the requirement for *Personal Identity Number (PIN) to be available in a SIM Card is defined by way of the GSM Standard GSM11.11. Moreover, GSM11.11 v3 1995 standard and onwards can be downloaded free of charge. So at least we know there is over 13 years of technical knowledge about SIM Card PIN that is traceable. Furthermore, there are other standards that are used to test for allocation and activation of PIN and the mandated execution of the function between the mobile phone and SIM Card.
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*Do remember that PIN is only used because it is comon language now, but has been made obsolete from the standards and replaced by CHV (Card Holder Verification).
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Finally, many ten of thousands of SIM Cards have been examined and their evidence, along with examiners' testimonies/experts' opinions, have been presented in criminal proceedings at Court for well over a decade. A large number of the SIM Cards presented for examination had PIN enabled, thus understanding the fundamental operation of PIN is vital to forensic investigation understanding and the evidence presented about it.
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I have sent copies of this Challenge and MOBILE FORENSICS AND EVIDENCE DEGREES/CHALLENGE (see weblink at the end of this discussion) to the following who have the responsibility for: innovation, universities and skills; and regulation of forensic sciences:
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Rt Hon John Denham Secretary of State for the
Department of Innovation, Universities and Skills (DIUS)
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Mr Andrew Rennison UK Forensic Science Regulator
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MOBILE FORENSICS AND EVIDENCE DEGREES/CHALLENGE

Thursday, January 08, 2009

SIM PIN Challenge

SIM PIN Challenge
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Back in 2005 I was at a presentation by a SIM manufacturer when the presentation turned to CHV (Card Holder Verification), the correct technical term for PIN used for SIM Cards.
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The presentation had reached the part "Verifying the CHV" and went on to record:
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~ To verify PIN, the verifyCHV APDU is used....
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A0 20 00 CHVNum 08 PINValue
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~ The message sent from the phone to the SIM in order to check your PIN number 1111, is:
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A0 20 00 01 08 313131FFFFFFFF
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This all seemed normal until three slides later when the presentation started to discuss "File Structure after personalization" and displayed the graphics starting with the Master File (MF) and under which there were five Elementary Files (EF). The graphics displayed in the presentation were text book style when discussing MF and EFs, except for this presentation the manufacturer had gone as far as to identify two particular CHV EFs; one of which was 3F00 - EF_CHV1 0000.
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So does that mean a particular EF under the MF in SIM with a logical address 3F00 0000 is always going to be the CHV1 file and would the raw data from that EF reveal a user's PIN number?
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Below are raw data extracts from three phases of SIM cards - Phase 1, Phase 2 and Phase 3 (2+) and harvested from the Master File (MF) 3F00 and an unnamed EF immediately under the MF with an address 3F00 0000.
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Your challenge, if you are interested, is to examine the raw data and corroborate whether the data reveals a user's CHV1 (PIN number) or not.
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To help, you may want to check the GSM SIM card standard GSM 11.11 to comprehend file structure, formatting and coding etc for elementary files and to learn what the standard has to say about CHV/PIN.
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As forensic investigators you shouldn't need the 'carrot and stick' approach to get you to undertake this challenge because I know how much you all love your work and can't get enough of it and that should be reward enough :-). However, the first person who posts the correct answer at Forensic Focus , I am sure we can sort out some sort of prize:
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http://www.forensicfocus.com/index.php?name=Forums&file=viewtopic&t=3349
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However, there are some rules (there is always something like this):
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1) In your answer it should contain identification to a document or weblink that supports the answer (the document/weblink must be traceable and not based on "something somebody told you"). This will be checked before any prize is awarded.
2) Challenge closes 15th February 2009.
3) I wont be giving the answer, because I do not want everyone just to sit back and think they can wait for my reply.
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GOOD LUCK
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PHASE 1 SIM Card
3F00
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Response: 00 00 1A 47 3F 00 00 00 F1 F4 44 13 15 83 02 03 04 00 82 8A 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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Allocated memory :1A47File ID :3F00
Type of file :MFNumber of DF : 2
Number of EF : 3 Number of CHV's : 4
CHV1(PIN1) :Disabled
CHV1(PIN1) Status :2 Tries left
CHV1(PIN1) Status :10 Tries left
CHV1(PIN1) Status :0 Tries left
CHV1(PIN1) Status :0 Tries left
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3F00:0000

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Response: 00 00 00 18 00 00 00 00 FF FF FF 13 06 00 00 02 01 00 00 0A FF
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File ID :0000
Type of file :RFU
Structure of file :Transparent
File Size :0018
Read Access :CHV (PIN) 15
Write Access :CHV (PIN) 15
Increase Access :CHV (PIN) 15
Rehabilitate :CHV (PIN) 15
Invalidate Access :CHV (PIN) 15
File Status :Not Invalidated
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Phase 2 SIM Card
3F00
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Response: 00 00 63 9C 3F 00 01 FF FF FF FF 01 0E 93 02 07 02 00 83 8A 00 00 00 00 83 00 FF
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Allocated memory :639C
File ID :3F00
Type of file :MF
Number of DF : 2
Number of EF : 7
Number of CHV's : 2
CHV1(PIN1) :Disabled
CHV1(PIN1) Status :3 Tries left
CHV1(PIN1) Status :10 Tries left
CHV1(PIN1) Status :0 Tries left
CHV1(PIN1) Status :0 Tries left
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3F00:0000

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Response: 00 00 00 12 00 00 04 00 FA FF FF 01 02 00 00
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File ID :0000
Type of file :EF
Structure of file :Transparent
File Size :0012
Read Access :CHV (PIN) 15
Write Access :CHV (PIN) 10
Increase Access :CHV (PIN) 15
Rehabilitate :CHV (PIN) 15
Invalidate Access :CHV (PIN) 15
File Status :Not Invalidated
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Phase 3 (2+) SIM Card
3F00
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Response: 00 00 00 01 3F 00 01 00 00 00 00 00 09 81 04 12 0A 00 83 8A 83 8A
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Allocated memory :0001
File ID :3F00
Type of file :MF
Number of DF : 4
Number of EF : 18
Number of CHV's : 10
CHV1(PIN1) :Disabled
CHV1(PIN1) Status :3 Tries left
CHV1(PIN1) Status :10 Tries left
CHV1(PIN1) Status :3 Tries left
CHV1(PIN1) Status :10 Tries left
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3F00:0000

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Response: 00 00 00 17 00 00 04 00 FB FF FF 01 02 00 00
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File ID :0000
Type of file :EF
Structure of file :Transparent
File Size :0017
Read Access :CHV (PIN) 15
Write Access :CHV (PIN) 11
Increase Access :CHV (PIN) 15
Rehabilitate :CHV (PIN) 15
Invalidate Access :CHV (PIN) 15
File Status :Not Invalidated
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Tuesday, December 02, 2008

Another ultra-thin membrane device

Another ultra-thin membrane device

John Lorne, Technical Officer for South Manchester GMP, having read the discussion in the thread "Ultra-thin membrane changes (U)SIM card usage"**, wants to raise awareness that, during his examinations, John has had firsthand experience with another similar device and emailed some comments to the webblog, along with the images below, which he thought would be of interest to readers
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John Lorne, Technical Officer:
"I have used one of these its named MT-SIM. They are for using one's phone on any network. It works by punching a small hole into your SIM and laying the contacts of the MT SIM onto the contacts of your SIM.
"The small hole is required as the chip on the MT SIM faces the opposite way (upwards and away from the SIM compartment) and is the same thickness.The MT SIM is not a solution for multi unlocking as it has to sit with its surrogate all the time (the MT SIM works by making the handset omit from asking the question on start up "what network are we on?") as soon as the MT SIM is seperate then the handset will revert to its network provider.
"I have tried this on a test phone for examination purposes and found it works and allows one to get into the handset. I lost my call history with this operation but I would've lost this in any case when I use my test SIMs (I use Motorola test SIM to bypass network issues, but in every case I lose call history, Focus 112 can recover this for me). In the end a colleague of mine asked could I unlock his daughter's phone to any network, it was a BB5 phone and at the time couldn't be unlocked in the more traditional way ie UFS/JAF box. I slid this in and it worked exactly as it said it would, so in some cases its actually quite advanced."

Tuesday, November 18, 2008

Ultra-thin membrane changes (U)SIM card usage

Ultra-thin membrane changes SIM card usage

Examiners may come across an ultra-thin (0.3mm) membrane that lays over the contacts of a SIM card. Called the V200 SIM Dialer, the membrane is "Prefix base programmable (For routing prefix and bypass prefix setting)". What does that mean? Well, it allows mobile phones installed with SIM Tool Kit menu (most up to date phones have them) and define access to the network. The point being, if you are looking for least-cost routing for calls or want to use a calling card, rather than have mobile network call charges, then this device makes that happen, apparently.

How does it do it? "Dial the desired number directly each time you call, SIM dialer V200 will automatically dial IP access in front of the dialed number".
As the manufacturer promotes, using their device will not change your dialling habits and there is "No cutting, No pounching your SIM".

As the device has been programmed, and looking at the on-board chip, there should be a reader for it or one could be constructed. This throws me back to the old days of ponyprog and PIC basics. Of course, of equal importance is how does this device impact when examining the handset and SIM card? Will manual examination be the only course for examination or do the current handset and SIM readers detect changes this device makes to them? What evidence is there for call history or data usage? These are just a few of the questions to get examiners started.


It seems this programmable ultra-thin membrane is not limited to just SIM calls, but there is a USIM version (U-SIM V33G) that can be used to unlock iPhones. There is a video that is useful to watch so that examiners can at least comprehend how ultra-thin the membrane is and how it is installed:-
http://tw.youtube.com/watch?v=JQSNJxis7Ds



Please note, this is not a promotion or advert for these products, the information provided is to assist examiners with observations about these devices that may form part of their evidence.

Saturday, November 01, 2008

Cloning Test SIM Cards

Cloning Test SIM Cards
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Cloning test SIM cards can present problems if their use is not carefully monitored and can lead to loss of data from a device under test (DUT). There appears many different instances under which the loss of data can occur when using a cloning test SIM card. Some examples are:
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- The inadequate level of notice and advice within the applications that create the clone test SIM card to precisely define that a particular Make/Model of handset has been tested using the cloning application before using with a partricular Make/Model or where the guide generally infers the application is usable with a particular Make.

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- Whether the cloned test SIM card has been correctly recorded or not, before inserting it into the device under examination (DUT).

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- The 'trial and error' approach being applied to evidential mobile phones leading to loss of data, where the written advice in the guide, when given, doesn't deal with the examination problem at hand.

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Taking one example of a mobile phone examination problem relating to the Samsung D880.
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This mobile phone is capable of having two SIM cards inserted, at the same time, in order to allow for two different subscriber accounts to be used separately by a user. To understand the difference compare the position when dealing with the traditional way of having to manually swop a SIM card with another in a device that is a single-inserted SIM card operating mobile phone.
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Once the user has selected to use one of the two SIM Cards inserted, the option to switch to a particular SIM in normal user mode is via the 'SIM selection key' with visual Icons displayed on the device's screen confirming which SIM and subscription account is in use.

Problematical for the examiner using cloned test SIM cards is what is the safest method for examining a dual SIM card mobile phone. Looking at some options, what problems can arise for the examiner:


1) Take out one of the user SIM cards and produce a cloned test SIM card, whilst leaving the other user SIM card in place? Then insert the new clone test SIM card and then examine the phone? It is unlikely this could work well because an original user SIM card is still in place, thus the mobile phone could still register to the network etc. That is so, because the examiner doesn't know which SIM and subscription account was last used by the mobile phone. The notion of switching the mobile phone 'ON' prior to using a cloned Test SIM card to find out begs the question why is the examiner using cloned test SIM cards in the first place?


2) Take out both user SIM cards and produce two cloned test SIM cards, but insert only one test card and examine on that basis? This might work, provided of course the examiner has selected for access the right SIM slot and subscription account, which is a bit 'trial and error', 'hit and miss'? Moreover, assuming the above method had worked and the examiner safely selected the correct SIM slot/account - for example by taking the pragmatic step of recording which user SIM came out of which slot and replacing the correct cloned test SIM card into the slot - what happens when the second cloned test SIM card needs to be inserted? Using the SIM selection key to switch to another SIM card may not assist because there isn't a cloned test SIM card in the second slot for the device to read any details. Moreover, bearing in mind the device memory has noted only one SIM inserted the first time around what impact might now happen if a second cloned test SIM card is inserted? Will it allow access to the subscriber account user data on the device? Furthermore, what happens when switching over to the other cloned test SIM card?



3) Inevitably, the line of reasoning in this discussion is intended to bring the reader's attention to the option of putting both cloned test SIM cards into the appropriate SIM slots and examining further from that standpoint. But what happens then if the device does not give up its riches and enables the examiner to gain access to the user data? Turning to the cloned test SIM cards guides, what if they provide no assistance at all? What if the cloning application may not record properly to the cloned test SIM card or the data that it does record are insufficient for a particular make and model of mobile phone to function in the way it is expected?
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In each of the above cases where loss of data might occur, that is to say e.g. where no call history or text messages are accesible, it may not be because the user has deleted them or the user has gone to settings to set a calendar event to delete texts or clear call history on a date and time, but may be because the cloned test SIM card may have removed access to them and the examiner may not be aware of that until either using a device reading program or conducting manual examination.

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The presumption suggested that the examination and the tools used to recover data from a device were functioning properly and without flaw at the time of the examination arising from the mobile phone data being served in evidence, inferring that it is safe to rely on, may not meet the maxim omnia praesumuntur rite esse acta, as expressed by Lord Griffiths in the case of R .v. Shepherd [1993] AC380. That can be so because it has never simply been solely about whether the original device (exhibit) was working properly at the material time, but of equal significance whether in the obtaining and the processes used to obtain data that the evidence is safe to rely on. The latter requirement did not disappear in the wake of the repeal of section 69 Police and Criminal Evidence Act 1984. Nor did it disappear by the introduction of the Criminal Procedures and Investigations Act 1996, The Police Act 1997, The Regulation of Investigatory Powers Act 2000 and so on.

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The purpose of raising this discussion (for examiners and students) about mobile phone forensic examination and tools it that discussions on these types of topics are not simply about providing answers and solutions to problems, but identifying potential questions that need to be adddressed before using cloned test SIM cards.

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Lastly, I have not described every event dealing with the examination of a dual SIM card mobile phone or how Samsung D880 manages the operation and functionality of both SIM cards. By not referring to these matters it has helped simplify and refine the discussion to keep the important points to the fore.