Do you know what “intermittent encryption” is? The ransomware gangs do and they are using it to avoid your detection.

Intermittent encryption is a recently detected method of obscuring malware from anti-virus software and other detection methods. It is not encryption of whole files, byte encryption of bytes within the malware. Research by SentinelOne has shown this evasion technique is being deployed by ransomware gangs in the wild:

Crimeware Trends | Ransomware Developers Turn to Intermittent Encryption to Evade Detection – SentinelOne

This illustrates why you must always be reviewing your cyber security – when we have better systems for stopping malware and ransomware the organised cyber criminal gangs do not simply pack up and go away, they find new ways to evade the defences.