{"id":617,"date":"2024-09-30T08:05:00","date_gmt":"2024-09-30T14:05:00","guid":{"rendered":"https:\/\/wpsites.ucalgary.ca\/jacobson-cpsc\/?p=617"},"modified":"2024-09-30T07:55:51","modified_gmt":"2024-09-30T13:55:51","slug":"breaking-the-cryptosystem-of-auto-keyless-entry-canada-auto-thefts-surge","status":"publish","type":"post","link":"https:\/\/wpsites.ucalgary.ca\/jacobson-cpsc\/2024\/09\/30\/breaking-the-cryptosystem-of-auto-keyless-entry-canada-auto-thefts-surge\/","title":{"rendered":"Breaking The Cryptosystem of Auto Keyless Entry, Canada Auto Thefts Surge."},"content":{"rendered":"\n

Imagine a sunny day setting in a coffee shop, peacefully sipping your Frappuccino drink, then someone next to you hijacks your car key fob without even touching it or talking to you.<\/strong><\/p>\n\n\n\n

A recent statistic by the Insurance Bureau of Canada (IBC) shows that auto theft insurance claims spiked to $1.5 billion in 2023 [3]. The numbers show a concerning car theft increase especially in the last four years, so what is the story?<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Canada nation wide auto claims 2023 [3]<\/p>\n\n\n\n

The Story of a Crypto Grabber \u201cFlipper Zero\u201d<\/strong><\/p>\n\n\n\n

According to Flipper Zero\u2019s website, the device was launched in 2020 as a community project [1]. $4.8 million was raised through a campaign on an online funding-raising platform called \u201cKickstarter<\/em><\/strong>\u201d [2]. The device was promoted as a portable multi-purpose gadget that helps security nerds and researchers in security penetration tests without a need to design sophisticated printed circuit boards (PCBs) [6]. The portability of this savvy tool made it widely adopted by the security community and led to an influx of a variety of creative open-source applications published by the community developers. Starting from cloning NFC cards to sniffing any radio frequency signals. Nevertheless, the tool was not available for legitimate use only, but also for malicious hackers as a new way of exploitation techniques.<\/p>\n\n\n\n

The federal Innovation, Science and Economic Development (ISED) linked the automobile theft surge to the flipper devices and revealed an investigation document (DGSO-003-24) spotting the strong relationship between the car theft surge and this emerging flipper as a crypto grabber<\/em><\/strong> [4].<\/p>\n\n\n\n

\u201cCode grabbers or crypto grabbers:<\/em><\/strong> devices designed to receive or copy the code emitted by a vehicle remote key to replicate and\/or transmit the copied code to access the vehicle.,\u201d posted by ISED.<\/em><\/p>\n\n\n\n

On February 8th<\/sup>, 2024, Canada’s federal government\u2019s public safety minister Dominic LeBlanc announced the banning of the Flipper Zero devices (Flippers) due to surging automotive thefts. These flippers can copy the wireless signals of the Remote Keyless Entry (RKE) fobs allowing offenders to steal any car without any traceability [5].<\/p>\n\n\n\n

How the Flipper Zero work?<\/strong><\/p>\n\n\n\n

Sending wireless codes from key fobs to a car securely has been an arena for vehicle theft crime since the mid-nineties. Initially, the key fob was a primitive design sending a fixed (static<\/em>) message from the fob to the car using a short Radio Frequency (RF). In a nutshell, the signal contains a static (fixed) frequency that maps to a specific function like opening the car doors. It was not a troubling effort for an intruder to break this system by capturing or sniffing the signal and reusing it repeatedly without needing the key fob anymore.<\/p>\n\n\n\n

With technology getting advanced and compacted, the Flipper devices just came perfectly to be a portable gadget as smaller as the keychain in size. Flippers are equipped with built-in local storage and various transceiver modules that can store signals and reemit them on target vehicles. It is not only easy to use but also can intercept fob signals without anyone noticing.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The Dilemma<\/strong><\/p>\n\n\n\n

The evolution of using computer boards in automobile manufacturing imparked on various anti-theft attempts, some of these were good yet are breakable. Rolling Number<\/em><\/strong>s (aka, Rolling Code<\/em><\/strong>) is one common anti-theft design that depends on the use of symmetric cryptography<\/em><\/strong> calculating a challenge code that must match both the car and the fob. The car would have a computer board that maintains a list of rolling numbers (generated incrementally and used in a sequential order). These rolling numbers are used in calculating a symmetric challenge code. Once the challenge is confirmed and matched, the car allows certain actions like door opening, etc. It is a symmetric system as each time the fob is pressed by the car owner, both the car and the fob must use the same rolling number to calculate and have a matching challenge code. Once a rolled number is used, the car removes it from the list, then the next expected rolling number is incremented for the next fob use. The car maintains a lengthy list of rolling numbers list that is enough for tremendous, and long fob usage. Here is an interactive demo to play the rolling numbers game (How Rolling Code Works (harryli0088.github.io) [9].<\/a><\/p>\n\n\n\n

Each challenge code is calculated as a combination of a serial number (which could be the Vehicle Identification Number or VIN) in addition to a rolling number from the maintained list. Now consider this situation, what if an attacker sends a rolling number faking it as your original fob? now the next expected rolling number is incremented, which means your intercepted fob now is out of sequence as it has an old number that has been removed already from the list. That is why I urge you, please do not try flippers in your car.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Flipper Zero Launches Campaign to Fight ‘Absurd’ Canadian Device Ban [12].<\/p>\n\n\n\n

While rolling numbers model is a good cryptography<\/em><\/strong> as it is hard to break the content of the signal and know the rolling number sequence, yet it is a breakable cryptosystem<\/em><\/strong>. The attacker did not need to know the content of the challenge code to break into the car. The implementation of this cryptosystem did not prevent the attacker from cloning the fob signal and retransmitting it again then accessing the car. The good side of this model though, is that the attacker can not reuse the same signal multiple<\/u><\/em> times. Also, copying the fob signal is possible only the if fob is pressed physically by someone and the attacker happens to be near to that signal to capture it.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Rolling Code, Securing keyless entry systems [9].<\/p>\n\n\n\n

The manufacturers realized a need to make it hard for the attackers to sniff the fob signals. Hence, a two-way communication is essential where the car\u2019s computer board and the key fob can communicate automatically confirming the symmetric challenge without even pressing anything on the fob. In modern cars nowadays, this typically happens when the car detects a fob in a close distance range, the car then sends a challenge code to the fob expecting a reply with a challenge code containing a correct rolling number. Once the challenge confirmation happens, the car ensures the challenge is correct and belongs to an authorized fob, then it allows the fob to perform certain actions like opening the door or even starting the engine. This is very similar to the same previous workflow except it initiates the communication automatically when there is a proximity between the car and the fob.<\/p>\n\n\n\n

Unfortunately, the attackers got cleverer coordinating the hacking attack using a two-phase method called the Relay Attack<\/em><\/strong>. In this type of attack, the attackers establish a side shadow communication channel where each obtains the challenge code without the need to have proximity between the car and the fob, as shown in the diagram below. In this exploitation, one attacker approaches the car with a transceiver faking itself as a fob, while the other attacker has another transceiver next to the fob faking itself as a car. Both attackers have a shadow private communication channel where they can retransmit the signals received from the car and authorized original fob, establishing the proximity but at a longer distance. Now think of the coffee shop story especially when go for coffee next time, please do not panic and start looking around.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

How the auto relay on attacks work [10]<\/p>\n\n\n\n

One puzzling point on the rolling number method as a symmetric cryptography implementation is, it lacks the sense of identity for the communicated devices. The Relay Attack<\/em> example shows that any attacker can fake being a car or a fob. The question now is how can the car and the fob be sure of the identity of the communicating devices? Yes, the answer is using asymmetric cryptography<\/em><\/strong> and digital signatures<\/em><\/strong>. However, this entails various questions and concerns. I really hope that we do not pay for annual fees to renew our car fobs.<\/p>\n\n\n\n

So, What Is Missing?<\/strong><\/p>\n\n\n\n

There are a few noticed issues in the current anti-theft models:<\/p>\n\n\n\n