Devices that intercept calls and text messages and dig into data stored on your mobile phone are being marketed to police departments across the United States “as being perfect for covert operations in public order situations.” Or, as the ACLU’s Privacy SOS blog puts it: protests.

IMSI, which stands for the dull and deceptively innocuous-sounding “International Mobile Subscriber Identity,” acts as a mobile phone tower that tricks cellphones into sending data to it instead of a nearby tower. Such “man-in-the- middle” attacks defy detection, usually occurring without the caller’s knowledge.

Police departments say they do not need warrants to use IMSI catchers. A case on the matter is working its way through the courts. The FBI already uses the device. Except for turning your cellphone off, there appears at the moment to be no way to shield yourself from such attacks.

Click through to Privacy SOS’ blog below to see an industry video and informational lecture on the devices.

— Posted by Alexander Reed Kelly

Privacy SOS:

Once it has made a connection with the phone and tricked it into thinking it is a mobile tower, the IMSI catcher forces the phone to drop its encryption, enabling easy access to the contents of the device. The tool then lets the attacker listen in on mobile conversations and intercept all data sent from a mobile phone, remaining undetected. In some cases the tool also allows the operator to manipulate messages.

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