Difference between pages "SIM Cards" and "Metadata"

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[[Image:Simpic.jpg|thumb|A typical SIM card.]]
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Metadata is data about data.  Metadata plays a number of important roles in computer forensics:
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* It can provide corroborating information about the document data itself.
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* It can reveal information that someone tried to hide, delete, or obscure.
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* It can be used to automatically correlate documents from different sources.
  
== SIM-Subscriber Identity Module ==
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Since metadata is fundamentally data, it suffers all of the data quality and pedigre issues as any other form of data. Nevertheless, because metadata isn't generally visible unless you use a special tool, more skill is required to alter or otherwise manipulate it.
  
The UICC (Universal Integrated Circuit Card) is a smart card which contains account information and memory that is used to enable GSM cellular telephones.  One of the applications running on the smart card is the SIM, or Subscriber Identity Module. In common parlance the term "UICC" is not used an the phrase "SIM" is used to describe the smart card itself.
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=Kinds of Metadata=
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Here are some kinds of metadata that are interesting in computer forensics:
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* File system metadata (e.g. MAC times, access control lists, etc.)
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* Digital image metadata. Although information such as the image size and number of colors are techncially metadata, JPEG and file formats store additional data about the photo or the device that acquired it.
  
Because the SIM is just one of several applications running on the smart card, a given card could, in theory, contain multiple SIMs. This would allow multiple phone numbers or accounts to be accessed by a single UICC. This is seldom seen, though there is at least one "12-in-1" SIM card being advertised at present.
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=File types that support metadata and extraction tools=
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;Exif
  
Early versions of the UICC used full-size smart cards (85mm x 54mm x 0.76mm).  The card has since been shrunk to the standard size of 25mm x 15mm x 0.76mm.
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=External Links=
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Wikipedia has a nice [http://en.wikipedia.org/wiki/Metadata entry on metadata].
  
 
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[http://www.drewnoakes.com/code/exif/ Metadata extraction in Java]
Although UICC cards traditionally held just 16 to 64KB of memory, the recent trend has been to produce SIM cards with larger storage capacities, ranging from 512MB up to [http://www.m-systems.com/site/en-US/ M-Systems'] 1GB SIM Card slated for release in late 2006.
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== SIM Security ==
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Information inside the UICC can be protected with a PIN and a PUK.
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A PIN locks the SIM card until correct code is entered. Each phone network sets the PIN of SIM to a standard default number (this can be changed via handset). If PIN protection is enabled, the PIN will need to be entered each time phone is switched on. If the PIN is entered incorrectly 3 times in a row, the SIM card will be blocked requiring a PUK from the network/service provider.
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A PUK is needed if the PIN is entered incorrectly 3 times and the SIM is blocked (phone is unable to make and receive calls/texts). The PUK can be received from the network provider, or possibly the GSM cell phone manual. '''Caution:''' if PUK is entered 10 times incorrectly, the SIM card is permanently disabled and must be exchanged.
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== SIM Forensics ==
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The data that a SIM card can provide the forensics examiner can be invaluable to an investigation. Acquiring a SIM card allows a large amount of information that the suspect has dealt with over the phone to be investigated.
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In general, some of this data can help an investigator determine:
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* Phone numbers of calls made/received
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* Contacts
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* [[SMS]] details (time/date, recipient, etc.)
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* SMS text (the message itself)
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There are many software solutions that can help the examiner to acquire the information from the SIM card. Several products include 3GForensics SIMIS [http://www.3gforensics.co.uk/products.htm], Inside Out's [http://simcon.no/ SIMCon], or SIM Content Controller, and Paraben Forensics' [http://www.paraben-forensics.com/catalog/product_info.php?products_id=289 SIM Card Seizure].
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The SIM file system is hierarchical in nature consisting of 3 parts:
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*Master File (MF) - root of the file system that contains
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DF’s and EF’s
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*Dedicated File (DF)
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*Elementary Files (EF)
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=== Data Acquisition ===
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These software titles can extract such technical data from the SIM card as:
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* '''International Mobile Subscriber Identity (IMSI)''': A unique identifying number that identifies the phone/subscription to the [[GSM]] network
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* '''Mobile Country Code (MCC)''': A three-digit code that represents the SIM card's country of origin
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* '''Mobile Network Code (MNC)''': A two-digit code that represents the SIM card's home network
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* '''Mobile Subscriber Identification Number (MSIN)''': A unique ten-digit identifying number that identifies the specific subscriber to the GSM network
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* '''Mobile Subscriber International ISDN Number (MSISDN)''': A number that identifies the phone number used by the headset
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* '''Abbreviated Dialing Numbers (ADN)''': Telephone numbers stored in sims memory
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* '''Last Dialed Numbers (LDN)'''
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* '''Short Message Service (SMS)''': Text Messages
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* '''Public Land Mobile Network (PLMN) selector'''
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* '''Forbidden PLMNs'''
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* '''Location Information (LOCI)'''
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* '''General Packet Radio Service (GPRS) location'''
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* '''Integrated Circuit Card Identifier (ICCID)'''
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* '''Service Provider Name (SPN)'''
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* '''Phase Identification'''
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* '''SIM Service Table (SST)'''
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* '''Language Preference (LP)'''
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* '''Card Holder Verification (CHV1) and (CHV2)'''
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* '''Broadcast Control Channels (BCCH)'''
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* '''Ciphering Key (Kc)'''
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* '''Ciphering Key Sequence Number'''
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* '''Emergency Call Code'''
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* '''Fixed Dialing Numbers (FDN)'''
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* '''Forbidden PLMNs'''
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* '''Local Area Identitity (LAI)'''
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* '''Own Dialing Number'''
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* '''Temporary Mobile Subscriber Identity (TMSI)'''
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* '''Routing Area Identifier (RIA) netowrk code'''
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* '''Service Dialing Numbers (SDNs)'''
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* '''Service Provider Name'''
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* '''Depersonalizatoin Keys'''
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This information can be used to contact the service provider to obtain even more information than is stored on the SIM card.
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== USIM-Universal Subscriber Identity Module ==
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A Universal Subscriber Identity Module is an application for UMTS mobile telephony running on a UICC smart card which is inserted in a 3G mobile phone. There is a common misconception to call the UICC card itself a USIM, but the USIM is merely a logical entity on the physical card.
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It stores user subscriber information, authentication information and provides storage space for text messages and phone book contacts. The phone book on a UICC has been greatly enhanced.
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For authentication purposes, the USIM stores a long-term preshared secret key K, which is shared with the Authentication Center (AuC) in the network. The USIM also verifies a sequence number that must be within a range using a window mechanism to avoid replay attacks, and is in charge of generating the session keys CK and IK to be used in the confidentiality and integrity algorithms of the KASUMI block cipher in Universal Mobile Telecommunications System (UMTS).
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In Mobile Financial Services, USIM seems to be a mandetory Security Element for user authentication, authorization and stored credentials. With the integration of NFC Handset and USIM, users will be able to make proximity payments where the NFS handset enables contactless payment and USIM enables independent security element.
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This is the evolution of the SIM for 3G devices. It can allow for multiple phone numbers to be assigned to the USIM, thus giving more than one phone number to a device.
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== Service Provider Data ==
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Some additional information the service provider might store:
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* A customer database
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* [[Call Detail Record]]s (CDR)
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* [[Home Location Register]] (HLR)
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== Service Providers that use SIM Cards in the United States ==
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* T-Mobile
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* Cingular/AT&T
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== Sim Card Text Encoding ==
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Originally the middle-European [[GSM]] network used only a 7-bit code derived from the basic [[ASCII]] code. However as GSM spread worldwide it was concluded that more characters, such as the major characters of all living languages, should be able to be represented on GSM phones. Thus, there was a movement towards a 16-bit code known as [[UCS-2]] which is now the standard in GSM text encoding. This change in encoding can make it more difficult to accurately obtain data form [[SIM cards]] of the older generation which use the 7-bit encoding. This encoding is used to compress the hexadecimal size of certain elements of the SIMs data, particularly in [[SMS]] and [[Abbreviated Dialing Numbers]].
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== Authentication Key (Ki) ==
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The authentication key or Ki is a 128 bit key used in the authentication and cipher key generation process. In a nutshell, the key is used to authenticate the SIM on the GSM network. Each SIM contains this key which is assigned to it by the operator during the personalization process. The SIM card is specially designed so the Ki can't be compromised using a smart-card interface. However, flaws in the GSM cryptography have been discovered that do allow the extraction of the Ki from the SIM card, and essentially SIM card duplication.
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== See also ==
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* [[SIM Card Forensics]]
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== References ==
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* [http://www.simcon.no/ SIMCon]
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* [http://www.sectorforensics.co.uk/sim-examination.shtml Sector Forensics]
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* [http://www.utica.edu/academic/institutes/ecii/ijde/articles.cfm?action=issue&id=5  IJDE Spring 2003 Volume 2, Issue 1 ]: [http://www.utica.edu/academic/institutes/ecii/publications/articles/A0658858-BFF6-C537-7CF86A78D6DE746D.pdf Forensics and the GSM Mobile Telephone System] (PDF)
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* http://en.wikipedia.org/wiki/Subscriber_Identity_Module
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Revision as of 18:42, 1 March 2006

Metadata is data about data. Metadata plays a number of important roles in computer forensics:

  • It can provide corroborating information about the document data itself.
  • It can reveal information that someone tried to hide, delete, or obscure.
  • It can be used to automatically correlate documents from different sources.

Since metadata is fundamentally data, it suffers all of the data quality and pedigre issues as any other form of data. Nevertheless, because metadata isn't generally visible unless you use a special tool, more skill is required to alter or otherwise manipulate it.

Kinds of Metadata

Here are some kinds of metadata that are interesting in computer forensics:

  • File system metadata (e.g. MAC times, access control lists, etc.)
  • Digital image metadata. Although information such as the image size and number of colors are techncially metadata, JPEG and file formats store additional data about the photo or the device that acquired it.

File types that support metadata and extraction tools

Exif

External Links

Wikipedia has a nice entry on metadata.

Metadata extraction in Java