Those aren't that crazy - it's a type of security screw. You'd need the bit to turn them the proper way, but your idea of a modified square drive sounds like it would work in a pinch.
For next time, I'd suggest either the Klein:
Or the
Xiaomi Wiha set:
I've got both - not because I'm precision screwdriver bit freak, but because my kid "borrowed" my Wiha set and lost the PH01 bit. Turns I can't find a cheap replacement to make the set whole again, so I just bought the Klein set to try something else.
Xiaomi is a Chinese brand. You'd think that would rule it out, but they only made the magnetic aluminum case and aluminum handle - both of which are quite good). Wiha makes the bits and, as you'd expect, they are great.
Reasons to pick the Xiaomi:
- Way more pocketable slim and sleek case
- Best quality bits
- Easier bit access (magnetic)
- Lighter
Reasons to pick the Klein:
- Easier to find locally
- Dual-length bit driver
- Better access to deeply recessed fasteners (longer bits and driver shaft)
- More bits (39 vs 24) - though I can't think of a time I needed a bit the Wiha lacked
They're both good kits. Neither is substantially superior in my opinion. The Xiaomi feels more like an office product due to it's sleek presentation (but that doesn't mean it isn't rugged). The Klein kit seems like something you'd keep in a shop and has even more bits to make sure you're prepared if you come across something weird.