14 May 2017
WannaCry does not use any heavy sophistication methods for delivery. It first uses a password protected zip file, which has a document inside.
Packaged this way anti-malware solutions cannot scan the attachment because they can’t enter the password for opening the attachment, although it is stated in the email body. Even APT (Advanced Persistent Threat) solutions may fail if they are not properly configured.
If your Anti-Phishing Awareness Training was successful, the chance of an infection is small.
In addition, it makes sense to block incoming mails with zip files, which cannot be inspected by the anti-malware solution. Don’t deliver them to the users junk mail folder, block them on the mail gateway.
This gives you the time to implement patch MS17-010, if you have not yet done so. Or isolate the affected systems from the network, if patching is not possible, e.g. in GxP controlled environments.