Imagine if you could send a message to every mobile phone in the country, pretending to be the President of the United States. What would you say How would people react Would anyone believe you
Well, it turns out that this is not just a hypothetical scenario. According to a recent study by researchers from the University of Colorado Boulder, it is possible to spoof a Presidential Alert using a consumer-grade software defined radio (SDR) and some open source software. And the worst part is, there is not much we can do to stop it.
Presidential Alerts are a special type of emergency notification that can be sent by the Federal Emergency Management Agency (FEMA) to inform the public about imminent threats or disasters. Unlike other alerts, such as weather warnings or Amber Alerts, Presidential Alerts are mandatory and cannot be disabled by users. They are also broadcasted nationwide, reaching every mobile phone in the country within seconds.
But how secure are these alerts How do our phones know that they are coming from a legitimate source and not from some prankster or malicious actor The answer is: not very.
The researchers found that the system that delivers these alerts, called the Commercial Mobile Alert Service (CMAS), has several design flaws that make it vulnerable to spoofing attacks. The main problem is that CMAS does not use any authentication or encryption mechanisms to verify the origin or integrity of the messages. This means that anyone with a SDR and some technical skills can create and broadcast fake alerts that look identical to the real ones.
To demonstrate this, the researchers used a BladeRF 2.0 and USRP B210 SDRs, which cost around $500 and $1200 respectively, and some open source software tools, such as OpenLTE and srsLTE. They also used a commercially available LTE femtocell, which is a small device that acts as a mini cell tower, with modified software. They performed their experiments inside a Faraday cage, which is a metal enclosure that blocks electromagnetic signals, to prevent interfering with real cell networks.
The researchers discovered that they could exploit a weakness in the way phones connect to cell towers. Normally, when a phone wants to connect to a tower, it has to go through an authentication process to prove its identity. However, this process takes some time, and during this time, the phone is vulnerable to receiving CMAS messages. The researchers found that they could trick phones into connecting to their fake tower by providing a stronger signal than the real ones. Then, they could send fake alerts to the phones before they realized that the tower was not authentic.
The researchers were able to send hundreds of fake alerts to various phones of different models and manufacturers within 45 seconds. The fake alerts looked exactly like the real ones, with the same sound, vibration, and visual appearance. The only difference was the content of the message, which could be anything the attacker wanted.
The researchers also found that there was no way for users to distinguish between real and fake alerts, or to report or block them. The only option was to turn off the phone or put it in airplane mode.
The researchers warned that this attack could have serious consequences if used maliciously. For example, an attacker could cause panic or confusion by sending false information about a natural disaster, a terrorist attack, or a nuclear war. Alternatively, an attacker could use the alerts to spread propaganda or misinformation, or to impersonate political figures or celebrities.
The researchers suggested some possible countermeasures to mitigate this attack. One option is to implement digital signatures on CMAS messages, so that phones can verify their authenticity before displaying them. Another option is to educate users about the possibility of spoofing attacks and how to react to them. However, they admitted that these solutions would require significant changes in the CMAS infrastructure and user behavior.
Until then, we might have to take every Presidential Alert with a grain of salt. ec8f644aee