In the wake of the recent Wannacrypt (also known as Wannacry) Ransomware attack, it appears evident from questions still regularly asked at Experts Exchange and other forums that some are still falling prey to Ransomware attacks, mostly due to not having applied appropriate available patches to their older operating systems.
As recently released security patches for Operating Systems that have already reached their End of Life cycle have not been made "automatically" available via Windows update, many seem to be struggling to find links to the patches they need, or indeed decipher and make sense of the (sometimes confusing) Microsoft pages, listing where patches can be downloaded.
With that out of the way, below I present a list of handy links to the patches you should make sure are installed in any of the operating systems listed that you may still be using. If you're unsure if you've installed the listed patches or not, I suggest downloading all those that are applicable to your system. If you don't need a patch when you try to install it, Windows will tell you so and you can just move onto the next one.