Cell Phone Attacks via SMS

January 1, 2011

The ThreatPost blog at Kaspersky Labs has another report from the 27th Chaos Communications Congress held recently in Berlin.  A presentation by Colin Mulliner and Nico Golde, of the Technical University of Berlin, described how cell phones could be attacked using specially crafted malicious SMS messages.   The results ranged from disconnection of an ongoing call to “bricking” the phone (rendering it completely inoperative).

The focus of attention recently in the cell phone market has been on “smart phones” (for example, the iPhone, or the various Android phones); this attack is noteworthy, in part, because it also works against older phones (sometimes called “feature phones”) that lack many advanced capabilities (such as E-mail or Web browsing).   Although these phones do not typically have a full-blown operating system, like Android or iOS, their operations are still controlled by firmware — software loaded into non-volatile memory by the vendor.  These devices still make up an estimated 85% of the world’s cell phones, and their firmware is updated only infrequently, if at all.

The economic motivation for replacing specialized devices with more general-purpose ones, controlled by software, is fairly clear, as is the attraction of introducing new features easily.  As with the introduction of “fly by wire” in aircraft, “smart” electricity meters, and “drive by wire” in automobiles, the replacement of dedicated hardware by software means that a whole new class of security vulnerabilities is introduced.

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