The communication protocol used by some of the latest generation of Implantable Cardioverter Defibrillators (ICDs) is weak enough to allow even attackers without advanced knowledge to reverse-engineer it and exploit vulnerabilities such as denial of service (DoS), security researchers have discovered.
In a paper (PDF) titled On the (in)security of the Latest Generation Implantable Cardiac Defibrillators and How to Secure Them, a group of six researchers from Leuven, Belgium, and Birmingham, UK, explain that Implantable Medical Devices (IMDs) use proprietary protocols for communication, and that limited or no security features are employed for wireless communication.
Because the protocols are used to carry out critical functions such as changing the IMD’s therapy or collecting telemetry data, an attacker capable of tapping into these communication protocols can perform privacy and Denial-of-Service (DoS) attacks. What’s more, the researchers explain that reverse-engineering the protocols is highly feasible even for attackers with limited knowledge and resources and without physical access to devices.
The research was conducted on the latest generation of a widely used ICD, which uses a long-range RF channel (from two to five meters) for communication, using a black-box approach and inexpensive Commercial Off-The-Shelf (COTS) equipment. While analyzing the protocols, the security researchers discovered weaknesses in them and in their implementations, and they also managed to conduct several attacks against the vulnerable devices.
These attacks, which include replay and spoofing, can put patients’ safety at risk, especially since they can be performed without being in close proximity to the patient. The security researchers suggest that the discovered issues affect at least 10 types of ICDs currently on the market and say that manufacturers have been contacted before the publication of the paper.
The researchers started their analysis with an attempt to intercept the wireless transmissions between the device programmer and the ICD, and focused on reverse-engineering the proprietary protocol used to communicate over the long-range channel. Next, they looked into ways to activate the ICD before carrying out attacks and discovered several ways to bypass the current activation procedure.
After fully reverse-engineering the proprietary protocol, the researchers focused on discovering vulnerabilities that an attacker could exploit, and revealed that active and passive software radio-based attacks such as privacy, DoS, and spoofing and replay attacks are possible. They also say that adversaries might not even need to be in the proximity of the vulnerable devices because sophisticated equipment and directional antennas could allow them to extend the attack distance by several orders of magnitude.
Some of the countermeasures that could mitigate or solve the discovered vulnerabilities include jamming the wireless channel when the ICD is in standby mode, sending a shutdown command so that the device would enter a sleep mode, and adding standard symmetric key authentication and encryption between the ICD and the programmer.
“We want to emphasize that reverse-engineering was possible by only using a black-box approach. Our results demonstrated that security-by-obscurity is a dangerous design approach that often conceals negligent designs. Therefore, it is important for the medical industry to migrate from weak proprietary solutions to well-scrutinized security solutions and use them according to the guidelines,” the security researchers say.
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