To create a security related task that is only visible to the acl*security group members, you must use the Report Security Issue form for new, and Protect as security issue option in the right menu for existing tasks.
To create a sensitive task that is restricted to WMF-NDA holders, you must use the New WMF-NDA Task form.
PermanentlyPrivate can be added to tasks known to contain sensitive information that can never be made public.
NOTICE: significant work related to this project was done as part of T244165