The United States Industrial Control Systems Cyber Emergency Response Team (ICS-CERT) issued an alert on Friday to warn relevant industries about a vulnerability affecting the Controller Area Network (CAN) bus standard.
CAN is a high-reliability serial bus communications standard. It’s present in most modern cars – it allows various components of a vehicle to communicate with each other – and it’s also used in the healthcare and other sectors.
A team of Italian researchers published a paper last year describing various CAN weaknesses and an attack method that can be leveraged for denial-of-service (DoS) attacks. They also published a proof-of-concept (PoC) exploit and a video showing how they managed to exploit the flaw to disable the parking sensors on a 2012 Alfa Romeo Giulietta.
The attack method presented by the experts requires physical access to the targeted vehicle and extensive knowledge of the CAN protocol, but ICS-CERT pointed out that it might be more difficult to detect compared to previously disclosed techniques.
“The severity of the attack varies depending on how the CAN is implemented on a system and how easily an input port (typically ODB-II) can be accessed by a potential attacker,” ICS-CERT said. “This attack differs from previously reported frame-based attacks, which are typically detected by IDS/IPS systems. The exploit focuses on recessive and dominate bits to cause malfunctions in CAN nodes rather than complete frames.”
Since CAN is a standard used across multiple industries and many products, patching vulnerabilities is not an easy task.
ICS-CERT says it’s working with vendors and researchers to identify mitigations for such attacks. In the meantime, the agency recommends limiting access to the OBD-II ports of a vehicle.
As cars become increasingly connected, researchers have invested significant effort into identifying potential security holes. A study conducted by IOActive last year showed that when it comes to cars, the CAN bus is the fourth most common attack vector.
Flaws that can be exploited for CAN access are also highly common, accounting for more than a quarter of the weaknesses analyzed by IOActive.
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