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New Threats to SMS-Assisted Mobile Internet Services from 4G LTE Networks

Mobile Internet is becoming the norm. With more personalized mobile devices in hand, many services choose to offer alternative, usually more convenient, approaches to authenticating and delivering the content between mobile users and service providers. One main option is to use mobile text service (i.e., short messaging service). Through associating an online account with a personal phone number, it aims to provide mobile-friendly, always-online, and even more secure experience. Such carrier-grade text service has been widely used to assist versatile mobile services, including social networking, banking, e-commerce, mobile-health, to name a few. However, as cellular network technology independently advances to the latest IP-based 4G LTE, we unfortunately find that these mobile services are somehow exposed to new threats raised by this change, particularly on 4G LTE Text service. In particular, messaging service over LTE has to shift from the a conventional circuit-switched (CS) design to the packet-switched (PS) paradigm as 4G LTE supports PS only. Due to this fundamental change, 4G LTE Text Service becomes inevitably open and possible to access. However, its shields to messaging integrity and user authentication are not in place, while the legacy security mechanisms deemed effective for 2G/3G text are in vain. As a consequence, such weaknesses can be exploited to launch attacks against a targeted individual, a large scale of mobile users and even service providers. These attacks are contactless without physically accessing to the victims’ devices. They might result in distressing account hijacking, realdollar loss and even spam lawsuits. Our study shows that 53 of 64 mobile services over 27 industries are vulnerable to at least one above threat, and some are even prone to million-dollar loss. We validate these proof-of-concept attacks in a controlled environment (a small scale of tests) in one major US carrier which supports more than 100 million users. We finally propose quick fixes and recommended remedies and discuss security insights and lessons we have learnt.