Well theoretically any piece of malware can spread to a SIM card (or any device capable of intercommunication) since interpreting signals between them will always leave room for errors. If these are exploitable then a person might be able to load malicious code onto it. However back to the real world this is near impossible since any malware capable of infecting a wide range of mobile devices are by far too large for a SIM card to hold (as in my SIM card having a capacity of 64K). Also as far as I know OEMs usually do not publish documentations about their SIM cards’ internals hence infected SIM cards, in theory, can exist, but in real life they don’t. For now.
