Sunday, February 15, 2009

Obama's BlackBerry brings personal safety risks


When the mainstream media first announced Barack Obama's "victory" in keeping his BlackBerry, the focus was on the security of the device, and keeping the U.S. president's e-mail communications private from spies and hackers.
The news coverage and analysis by armchair security experts thus far has failed to focus on the real threat: attacks against President Obama's location privacy, and the potential physical security risks that come with someone knowing the president's real-time physical location.

Serial numbersBefore we dive in, let's take a moment to note that each mobile phone has a unique serial number, known as an IMEI, or MEID. This unique number is transmitted in clear text, every time the phone communicates with a nearby cell tower. Thus, while the contents of a phone call or the data session (for e-mail) are usually encrypted, anyone with the right equipment can home in on a particular IMEI and identify the location of the source of that signal.
The most common device used to locate a phone by its IMEI is a "Triggerfish", a piece of equipment that is routinely used by law enforcement and intelligence agencies. This kind of device tricks nearby cell phones into transmitting their serial numbers and other information by impersonating a cell tower.
The devices, which are actually fairly low-tech, were used to hunt down famed hacker Kevin Mitnick back in the 1990s. Most interesting of all, according to Department of Justice documents, Triggerfish can be used to reveal a suspect's location "without the user knowing about it and without involving the cell phone provider."
The expensive brand-name Triggerfish devices, made by the Harris Corp., are sold only to government agencies. However, it is almost certain that foreign governments have similar technology. Furthermore, someone with a low budget could likely use the open-source GNU Radio platform, which can already decipher GSM signals, to roll their own phone sniffer.
Finding ObamaWe know that the president has been given a White House-issued BlackBerry phone. As a result, Obama's smartphone is broadcasting its IMEI serial number for anyone with the right equipment to detect.
Of course, the president is never alone, and so it is likely that anyone sniffing the wireless spectrum near the president would pick up hundreds of different BlackBerrys in the area.
However, Obama's aides do have to go home at some point, whereas Obama sleeps at the White House. This means that over the course of several days or weeks, it should be possible for a patient adversary to determine which IMEI belongs to the president's phone, and which IMEIs are associated with the phones of aides, simply by following the president (at a distance) and monitoring the spectrum at all hours.
As staffers go home for the evening, and Secret Service agents rotate out of duty, an adversary can strike their IMEI numbers off of the list. Within days, that initial list of 100 BlackBerrys can be reduced down to a single IMEI identifying the president's phone
Were someone to learn the president's IMEI, they could use it to gain valuable (and dangerous) information. For example, by pointing an antenna at the White House, it'd be possible to instantly determine if the president was inside. With a sophisticated-enough antenna, it might even be possible to determine which vehicle the president is sitting in while traveling in a motorcade, or to determine if the Secret Service is driving an empty limousine along a high-profile route to draw attention, while the president travels to a venue in an unmarked vehicle. The digital trail left by the president's BlackBerry would soon announce his presence to those keeping an eye out for his IMEI.
I am sure that others could come up with even more nefarious uses for real-time access to the president's physical location. I will leave that task to the blogosphere.


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