Crypto ransomware

My question may be off-topic but would hashcat be useful for trying to find private keys used in crypo ransomware ?
I presume cryptowall uses an RSA-2048 encryption.

Or would it be too huge/greedy ?

Thank you for your advices.
Don't think so
If the 2048 bit private/public keys were generated with secure recommendations in mind (resistance to Fermat's etc.), then there's nothing we can do without quantum computers.

And no, NFS has nothing to do with hashcracking, so hc isn't of any use for it.