The update doesn’t need any manual intervention and disables banned plugins affecting Flash and Java, via Apple’s Xprotect file update. “To help protect users from a recent vulnerability, Apple has updated the web plug-in-blocking mechanism to disable older versions of the web plug-in: Adobe Flash Player” reads the knowledge base article.
Apple has resorted to such a measure since Adobe released an emergency Flash update after three major vulnerabilities were found affecting Windows, Mac an Linux OS and two of them were already exploited in Firefox that used FlashPlayer plugin. The minimum version of Flash player plug-in required is 11.6.602.171 and you can find instructions on how to update your existing plug-in here.
Apple has recently blocked a number of plug-ins and third party add-ons which could be used in a malicious manner by computer hackers. Two weeks ago it blocked Java on its devices after a hacking incident involved computers of Apple, Microsoft and Facebook employees.