I know nothing really, but bitparking and eligius pool require no registration and a botnet could use that to their favor.

But why use a pool at all? If a botnet is big enough to generate whole blocks then they should all solo mine but have the generation sent to the bonnet operators wallet, and if the botnet  is not big enough to generate blocks, then it's a waste of time to even write the malicious code.

In any case, to write a botnet is really really bad and I'm sure you mum would be disappointed in the person who did. So don't.