Sentence:  Due to their non-invasive, non-harming manner, and the rarely available and the yet more rarely implemented proper countermeasures, <WSD>sidechannel</WSD> attacks are a particularly dangerous attack method against many vehicular IT security mechanisms. 
Meaning of the word marked with <WSD> tags:  (security) An indirect source of information about what a system is doing, such as execution time, version number, etc.