Not a whole lot. The fastest CPUs will net you less than 100 MH/s [0]. The fastest single-card GPU configurations will net you around 1,000 MH/s [0]. The current total hash rate is around 5,000,000,000,000 MH/s [1]. WannaCry affected around 300,000 PCs [2]. So if every WannaCry miner was operating off CPU and getting 100 MH/s, it would only be 30,000,000 MH/s. Or 0.0006% of the current total hash rate. If they all had high-end GPUs getting them 1,000 MH/s then that would bring it up to 300,000,000 MH/s. Or 0.006% of the current total hash rate. So WannaCry wouldn't even be a drop in the bucket. If you're wondering how the hash rate is so high, it's because mining has switched to using ASICs, the fastest of which run around 14,000,000 MH/s [3].<p>[0] <a href="https://en.bitcoin.it/wiki/Non-specialized_hardware_comparison" rel="nofollow">https://en.bitcoin.it/wiki/Non-specialized_hardware_comparis...</a><p>[1] <a href="https://blockchain.info/charts/hash-rate" rel="nofollow">https://blockchain.info/charts/hash-rate</a><p>[2] <a href="https://en.wikipedia.org/wiki/WannaCry_ransomware_attack" rel="nofollow">https://en.wikipedia.org/wiki/WannaCry_ransomware_attack</a><p>[3] <a href="https://en.bitcoin.it/wiki/Mining_hardware_comparison" rel="nofollow">https://en.bitcoin.it/wiki/Mining_hardware_comparison</a>