Hello, Those are TA, tamper-resistant heads. These are often found in security bit kits.
I just use a flat blade jeweler’s screwdriver. Very little torque will be required to tighten these fasteners. Usually I can just hold pressure against the head and turn the nut.
As always, use caution not to overtighten metal fasteners when used with plastic parts.
Edit: I should have just posted this link.