How to set session cookie (.sid) as secure?

Hello, I know that there’s a setting for the .auth cookie to be secure, and it works. But how can I achieve this for the .sid cookie? (the session cookie as far as I understand) *My app is going through a security audit and I have to accomplish this in order to be able to deploy to production servers…

I’ve been trying under config.js, but I haven’t succeeded.

Thanks!