Mobile Phone Forensics Michael Jones

Overview Mobile phones in crime The mobile phone system Components of a mobile phone The challenge of forensics So many handsets, so little time… Michael Jones2Mobile Phone Forensics

Mobile Phones in Crime Direct: the phone as an instrument of crime – Terrorism – Cyber bullying Indirect: the phone as an accessory – Contacts – Phone calls and messaging General – The phone is a ‘must have 24/7’ device Michael JonesMobile Phone Forensics3

Data Recovered from a Mobile Phone Same questions as for all investigations Is the data valid? – Is it an accurate reflection of events? – Is it complete? Is the data reliable? – Are the measurements accurate? – Could they have been tampered with? Michael JonesMobile Phone Forensics4

The Mobile Phone System First mobile telephone system was developed and inaugurated in the U.S. in 1945 in St. Louis, Missouri. – Bell Laboratories were responsible for most developments The system (still, today) uses a number of hexagonal ‘cells’ that handle connections with mobile devices Cells use different frequencies Communication is full duplex Michael JonesMobile Phone Forensics5

Mobile Phone Generations 1G – Analogue 2G (includes 2.5, 2.75) – Digital, mostly GSM, circuit switched 3G – High speed IP data networks and mobile broadband), packet switched 4G – All IP networks. Use of Internet, LAN, etc. Michael JonesMobile Phone Forensics6

Cell Phone Channels Carriers are allocated a number of channels per city/geographical area – One channel = 1 form of communication There is therefore a capacity on each cell – Each phone call needs 2 channels for full duplex – And some channels are reserved for control communications Michael JonesMobile Phone Forensics7

Making a call The caller’s phone sends a request to the nearest cell – The cell controlling the callee is then located – The request is then sent to that phone And the phone rings When a person moves – There is a handover to the nearest cell Many issues with this Michael JonesMobile Phone Forensics8

Components of a Mobile Phone IMEI number – International Mobile Equipment Identity – Unique at the point of manufacture SIM card – Subscriber Identity/Identification Module – Includes: service-subscriber key (IMSI) security authentication and ciphering information temporary information related to the local network a list of the services the user has access to two passwords (PIN for usual use and PUK for unlocking) – Uses Public Key Infrastructure (PKI) Michael JonesMobile Phone Forensics9

Capture – Should the phone be turned off? – What about fingerprints? Investigation – Where is the data? SIM card Phone memory – How to access the data? Michael JonesMobile Phone Forensics10

Accessing the Data Types of access – Physical and logical Logical – Most phones use a proprietary storage format This may be becoming less common This complicates investigation of physical acquisition – The meaning of what is stored is often not clear Many manufacturers include their own ‘features’ Michael JonesMobile Phone Forensics11

A Forensic Investigation Need to use a forensic investigation ‘kit’ This reads the data in a forensically sound manner – Read only, write blocking The kit needs to have – All the relevant connectors and battery connections – Up-to-date software to locate and read the data Michael JonesMobile Phone Forensics12

Communications SIM card reader WiFi Bluetooth Michael JonesMobile Phone Forensics13

What Data is Included? Logs – Calls, missed calls, SMS messages Contacts – Including ‘speed dial’ numbers Locations – If GPS enabled Michael JonesMobile Phone Forensics14

Issues Multiple phones – Have you captured all relevant phones? Pay-as-you-go – Unregistered phones Multiplicity of phones – Thousands of models available – Most with proprietary OS and filing systems Time and cost Storage – Faraday bag Michael JonesMobile Phone Forensics15

Summary Mobile phones are a valuable source of data – Location(s) – Activities Most people own at least one – And phones are (generally) reliably unique Criminals are aware of the capabilities of mobile forensics Michael JonesMobile Phone Forensics16