The algorithm looks pretty trivial. All it does is take the mac address, reverse the byte ordering, and use the result modulo 999999929.

That's probably simple enough that even I could read it in assembly and figure it out. I don't know if getting a firmware image is difficult, but the actual generator certainly isn't the hard part here.

I'm wondering if that modulo value has any meaning - looking at it in a few different formats hasn't immediately struck any sparks with me.

It wasn't leaked. The obvious vulnerability made it trivial to write up a script to demonstrate it, which is all the researcher did.

or a smart reverser :)