Most of what libraries do technologically is now outsourced to SAAS companies that specialize in the library space (there are at least 2 major one in the US, and I think at least 3 or 4). (encore and bibliocommons are the 2 major ones that I remembered and am pretty sure I've seen at least 2 others).

If everything you are doing is in the cloud, I'd argue that recovering from a ransomware attack is more of a question of if the SAAS company did its job right (which it should be more capable of handling). Of course, that's a reasonable question if they did (similarly why I prefer paying with paypal or google or even (as not so common) amazon third party payment systems than a retailers own internal payment system, yeah they might screw up too, but they invest a lot more into not screwing it up).