The Need for a Faraday Bag

Fri, 02/21/2014 - 9:44am
Eamon P. Doherty
Cell phones are devices that connect to telecommunication networks through wireless signals. Some cell phones can also connect to Bluetooth devices or wireless networks. If the security features are not enabled on the cell phone, then it may be possible to connect to the phone and alter, delete, or add digital evidence to the phone. It is very important that the digital evidence be preserved from the time of seizure until it is presented as evidence in court. If evidence is suspected of being tampered with, it could be ruled as inadmissible in court. Therefore, it is important for CCEs to preserve digital evidence by using a Faraday bag and noting its usage on the chain of evidence form. Smith and Bace, authors of a forensic testimony book, discuss the importance of preserving evidence and protecting the integrity of digital evidence.
Faraday bags look very similar to antistatic bags. The difference is that the antistatic bag prevents damage to the device from small electrical charges that have built up and are discharged from static electricity, but it does not protect the device from outside connectivity. Static bags are obtained commonly when purchasing electronic equipment such as a wireless weather station, computer memory chips, or an EZPass transponder for the car that makes it convenient to pay tolls. The Faraday bag is based on the concept of a Faraday cage. The Faraday cage is an enclosure that prevents outside signals from penetrating the cell phone or examination equipment. The Faraday bag is made with materials that block wireless signals from entering the bag, thus protecting the integrity of the device in the bag from outside influences.
The Faraday bag will not prevent the device from internal data alteration by items such as logic bombs. A logic bomb is set to go off if certain conditions are met. If a person was supposed to simultaneously press a set of keys daily to keep a destructive program from running on the cell phone, this would be one example of a logic bomb. The phone that was seized from someone may be protected from outside control of hackers with the use of a Faraday bag, but the phone may be victim to a logic bomb if certain conditions are not met while the phone is in possession of the CCE.

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