Linux and automotive computing security

CAN itself is no worse than Ethernet, except for speed and packet length limitations. On the contrary, it offers several benefits over plain ethernet, such as built-in QoS and a much lower cost to deploy.

The difference is that there are several standard abstraction layers built on top of ethernet which provides additional features, including some security features. Unfortunately these abstraction layers are way to complex to run on the 20 kHz, 8 bit system with 64 kB RAM you typically see in a sensor, leaving you the options of raw ethernet, raw CAN, or raw RS-232 for connectivity.

When given those choices, using CAN is usually a pretty good option, you just have to remember its limitations and design your application protocol with security in mind, as you wont "inherit" any from the underlying protocol, like you do with TCP/IP. (Though that is probably true anyway, as the security features of TCP/IP are quite limited).