JTAG, Chip Off, and ISP Extractions of Data from Mobile Phones
Three common forensic techniques are used to extract data from mobile phones.
1. A JTAG (Joint Test Action Group) involves soldering wires to JTAG ports in order to connect to a processor which can create an image from the memory card of the phone. An example of a JTAG connection is shown here, on the website of Farley Forensics.
2. ISP (In System Programming) extractions are used when no JTAG or test access points (TAPs) are available, and the examiner has to solder a connection directly to the board.
With both JTAG and ISP connections the wires are connected to outside hardware, such as the Medusa Pro or Easy JTAG box.
3. Chip Off extractions are generally performed when JTAG or ISP extractions are not possible. This approach involves physically removing the memory card from the phone. The data on the chip can then be collected using a reader specifically designed for the chip. Devices exist which include adapters for all of the chips commonly used in smartphones.
Each of these techniques allows data on a passcode protected phone to be accessed, but not data on an encrypted phone. These methods are used when the logical, physical, and file system acquisition of data is limited or not possible.