I am trying to come up with some ideas for writing up an enforcer droid for the player characters to take on at some point, it would be the same type of droid that K2SO was. They seem pretty sturdy, but they also lack built in weapons. Originally I was tempted to go with the security droid stats found in the back of the book but those don't strike me as what I need, and I was wondering if other people here had any suggestions.

The LE droid in Far Horizons would work.

Rival version: Brawn 4 Agility 2 other stats 1. WT 15, Soak 6 (integrated "heavy clothing"), Droid Traits. Applicable skills rank 2 (probably Brawl, Coercion, Discipline, Vigilance, maybe a Ranged skill, etc.). That's what I'd spitball up, anyway.

K2SO would also seem to have a high intellect, it's a good mechanic/slicer and analyst. perhaps a 3 with a couple of skill ranks. But how much of K2SO was unique to K2SO and how much is standard?

Dang good point Richardbuxton, forgot about that! Intellect 3 I'd say.

Or they have an implanted cyber jack lowers difficulty of slicing by 1 for 2 strain.

K2SO was probably upgraded over a normal security droid. Why would you need a thug-droid to hack or be good at analysis? Good awareness, sure, beyond that you're just throwing away creds, and the Empire did seem to have a thing for "either the cheapest thing that gets the job done, or an outrageously expensive oversized and overpowered thing/superweapon, and nothing in between."

He was definitely re-programmed, so the additional functionality probably came from that.

Yep that's what I thought, a stat line of 4,2,2,1,1,1 would suffice. Then training in combat, warfare, perhaps Piloting Planetary and Coercion.