WannaCry is the latest ransomware to sweep the internet and cause lots of excitement. As occasionally happens with well publicized security events like this I got to hear a former firewall admins favorite words: "Can you please take away a bunch of network access?" What fun!
I love blocking traffic as much as the next guy, but it's not a great idea to just change firewall rules willy nilly. You should always spend a little time thinking about the impacting and looking at what access it's prudent to remove. In this post I'll list a couple of the commands I used to poke around our AWS Security groups and find where SMB was allowed.