Fileless threats and ransomware aren’t new, but a malware that incorporates a combination of their characteristics can be dangerous. Take for instance the fileless, code-injecting ransomware we’ve uncovered—SOREBRECT, which Trend Micro detects as RANSOM_SOREBRECT.A and RANSOM_SOREBRECT.B.

http://blog.trendmicro.com/trendlabs-security-intelligence/analyzing-fileless-code-injecting-sorebrect-ransomware/