HDDCryptor, sometimes spelled HDD Cryptor and also identified as Mamba, is a new ransomware variant. It rewrites a computer’s MBR (Master Boot Record) boot sectors and locks users out of their PCs. Trend Micro says the ransomware reaches computers after users download files from malicious websites. In January, the ransomware authors were asking for the equivalent of $700 in Bitcoin, as one of the victims that posted on Bleeping Computer revealed. In August-September infections now use a six-digit identifier instead.
Source: https://www.bleepingcomputer.com/news/security/hddcryptor-ransomware-overwrites-your-mbr-using-open-source-tools/