US Patent 11392695 Detecting ransomware

There is disclosed in one example a computer-implemented anti-ransomware method, including: selecting a file for inspection; assigning the file to a type class according to a file type identifier; receiving an expected byte correlation for the type class; computing, according to a byte distribution of the file, a byte correlation for the file; comparing, via statistical analysis, the byte correlation to the expected byte correlation; and determining that the file has been compromised, including determining that the file has a byte correlation that deviates from the expected byte correlation by more than a threshold, taking a ransomware remediation action for the file.