The hacking group TeamTNT has been spotted by the security company AquaSec attempting to hijack servers to run malware used to break Bitcoin encryption:
TeamTNT hijacking servers to run Bitcoin encryption solvers (bleepingcomputer.com)
The task is computationally intensive but if enough servers are compromised and a wide enough distributed computer created, the attack is worth the threat actor’s efforts, as you will be paying for the computer resources and power for them.