Global Positioning System
The Global Positioning System (GPS) is a satellite navigation system.
There are several places where GPS information can found. It can be very useful for forensic investigations in certain situations. GPS devices have expanded their capabilites and features as the technology has improved. Some of the most popular GPS devices today are made by TomTom. Some of the other GPS manufacturors include Garmin and Magellan.
TomTom provides a wide range of devices for biking, hiking, and car navigation. Depending on the capabilities of the model, several different types of digital evidence can be located on these devices. For instance, the TomTom 910 is basically a 20GB external harddrive. This model can be docked with a personal computer via a USB cable or through the use of Bluetooth technology. The listed features include the ability to store pictures, play MP3 music files, and connect to certain cell phones via bluetooth technology. Data commonly found on cell phones could easily be found on the TomTom910. Via the Bluetooth, the TomTom can transfer the entire contact list from your phone. The GPS unit also records your call logs and SMS messages. Research needs to be done to see if the TomTom stores actual trips conducted with the unit. This would include routes, times, and travel speeds.
The TomTom unit connects to a computer via a USB base station. An examiner should be able to acquire the image of the harddrive through a USB write blocker. If not, it may be necessary to remove the hard drive from the unit.
TomTom models such the TomTom One Regional, TomTom Europe, Go 510, Go 710 and the Go 720 store map data, favourites, and recent destinations on a removable SD card. This allows the forensic examiner to remove the SD card and make a backup with a write blocked SD card reader. The most important file for the forensic examiner will be the CFG file that is held in the map data directory. This holds a list of all recent destinations that the user has entered into the device. The information is held in a hex file and stores the represents grid coordinates of these locations.
Certain TomTom models (Go 510, Go 910, Go 920 etc.) allow the user to pair their mobile phone to the device so they can use the TomTom as a hands free kit. If the user has paired their phone to the TomTom device, then the TomTom will store the Bluetooth MAC ID for up to five phones, erasing the oldest if a sixth phone is paired. Depending on the phone model paired with the TomTom, there may also be Call lists, contacts and text messages (sent & received) stored in the device too. Automated forensic analysis for TomTom GPS units is possible with software from Digivence - Forensic Analyser - TomTom Edition. Sample Report
Digital Camera Images with GPS Information
Some recent digital cameras have built-in GPS receivers (or external modules you can connect to the camera). This makes it possible for the camera to record where extactly a photo was taken. This positioning information (latitude, longitude) can be stored in the Exif metadata header of JPEG files. Tools such as jhead can display the GPS information in the Exif headers.
Cell Phones with GPS
Some recent cell phones (e.g. a Motorola EZX phone such as the Motorola A780) have a built-in GPS receiver and navigation software. This software might record the paths travelled (and the date/time), which can be very useful in forensic investigations.