Mirai variant that featured Bitcoin mining module stopped distribution after March 27. Bitcoin mining is the process of performing CPU and GPU-intensive mathematical operations. IBM X-Force team says the Bitcoin mining feature was never deployed. Mirai botnets are more profitable when used for DDoS attacks or as relay points to redirect malicious traffic for other crooks. Currently, there’s also a Mirai version that uses Windows workstations as intermediaries for infecting IoT devices. Last week, researchers from Radware discovered a new IoT malware variant called BrickerBot.
Source: https://www.bleepingcomputer.com/news/security/mirai-botnet-temporarily-adds-bitcoin-mining-component-removes-it-after-a-week/