Petya has always been known for the peculiar manner in which it encrypts an affected disk. The first version of the malware needed a reboot before the bad stuff would happen, so security researchers found a vaccine that would stop the machine from rebooting. This new version seems to feature the proper Salsa20 algorithm, SecurityWeek reports. In the past, the malware used spam emails disguised as job applications as a spear phishing technique. It seems prudent to steer clear of such emails unless you are certain that they come from trusted sources.”]
Source: https://securityintelligence.com/news/petya-ransomware-upgrades-its-crypto/