I'd like to take a moment to promote the new ArcGIS for Server Security Update 2 Patch, released just yesterday.
This update may be found here:
This patch is available for the final releases of each version, meaning 10.2.2 and 10.3.1.
Esri recommends that all customers using ArcGIS Server 10.2.2 and 10.3.1 apply this patch.
Customers who are using 10.2 or 10.2.1 should first apply 10.2.2.
Customers who are using 10.3 should first apply 10.3.1.
Note that to preserve conflicts for users with previously installed patches and fixes, the security patch includes many other fixes in addition to traditional ‘security’ issues. Details regarding the fixes included in this update are documented in the patch documentation referenced above.