Abstract
Modern cell phones are required to receive and display alerts via the Wireless Emergency Alert (WEA) program, under the mandate of the Warning, Alert, and Response Act of 2006. These alerts include AMBER alerts, severe weather alerts, and (unblockable) Presidential Alerts, intended to inform the public of imminent threats. Recently, a test Presidential Alert was sent to all capable phones in the U.S., prompting concerns about how the underlying WEA protocol could be misused or attacked. In this paper, we investigate the details of this system and develop and demonstrate the first practical spoofing attack on Presidential Alerts, using commercially available hardware and modified open source software. Our attack can be performed using a commercially available software-defined radio, and our modifications to the open source software libraries. We find that with only four malicious portable base stations of a single Watt of transmit power each, almost all of a 50,000-seat stadium can be attacked with a 90% success rate. The real impact of such an attack would, of course, depend on the density of cellphones in range; fake alerts in crowded cities or stadiums could potentially result in cascades of panic. Fixing this problem will require a large collaborative effort between carriers, government stakeholders, and cellphone manufacturers. To seed this effort, we also propose three mitigation solutions to address this threat.
Highlights
The Wireless Emergency Alerts (WEA) program is a government mandated service in commercialized cellular networks in the U.S WEA was established by the Federal Communications Commission (FCC) in response to the Warning, Alert, and Response Act of 2006 to allow wireless cellular service providers to send geographically targeted emergency alerts to their subscribers
We present our threat analysis on the commercial mobile alert service (CMAS) spoofing attack and implement an effective attack system using commercial off-the-shelf (COTS) software-defined radio (SDR) hardware and open-source Long-Term Evolution (LTE) software
EVALUATION Figure 7 illustrates our experimental testbed setup, which consists of an Evolved Packet Core (EPC) and eNodeB for a conventional LTE system, a malicious eNodeB for spoofing, and cell phones for victim User Equipment (UE)
Summary
The Wireless Emergency Alerts (WEA) program is a government mandated service in commercialized cellular networks in the U.S WEA was established by the Federal Communications Commission (FCC) in response to the Warning, Alert, and Response Act of 2006 to allow wireless cellular service providers to send geographically targeted emergency alerts to their subscribers. We demonstrate how to launch a Presidential Alert-spoofing attack and evaluate its effectiveness with respect to attack coverage and success rate To answer this question, we start by looking into the alert delivery method used by WEA. WEA sends alerts via the commercial mobile alert service (CMAS), which is the underlying delivery technology standardized by the 3rd Generation Partnership Project (3GPP). These alerts are delivered via the LTE downlink within broadcast messages, called System Information Block (SIB) messages. Responsible disclosure In January 2019, before public release, we disclosed the discoveries and technical details of this alert spoofing attack to various pertinent parties These parties include the government and standardization organizations FEMA, FCC, DHS, NIST, 3GPP, and GSMA; the cellular network service. Providers AT&T, Verizon, T-Mobile, Sprint, and U.S Cellular; and the manufacturers Apple, Google, and Samsung
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