Edit: It seems that this system creates a whole load of bogus files and dirs and monitors them, not the whole file system. This pollutes the file system and means that people can quite easily write around it.

Every ransomware program goes over files, chooses the ones that look interesting, encrypts them and destroys the originals. You know what else does this? Compression software, legitimate encryption applications and backup and cloud-sync solutions in addition to many more programs. The same behavior is exhibited even if you manually compress a directory with a password and then delete it. Since ransomware encrypts any file anywhere on a computer, it’s extremely difficult to distinguish a legitimate file activity from a malicious one. While every encrypted file increases the likelihood that the ransomware will be detected, each encrypted file equals another important piece of information lost. Every second counts when ransomware starts encrypting files.

Cybereason RansomFree: Behavior – Based Ransomware Blocking Freeware

Cybereason researched more than 40 ransomware strains, including Locky, Cryptowall, TeslaCrypt, Jigsaw and Cerber and identified the behavioral patterns that distinguish ransomware from legitimate applications. Whether a criminal group or nation created the program, all ransomware functions the same way and encrypts as many files as possible. These programs can’t determine what files are important so they encrypt everything based on file extensions.

RansomFree, Cybereason’s behavioral anti-ransomware free tool, takes all these challenges into consideration. By putting multiple deception methods in place, RansomFree detects ransomware as soon as encryption occurs either on a computer or network drive. Once encryption is detected, RansomFree suspends it, displays a popup that warns users their files are at risk and enables them to stop the attack.

RansomFree protects against local encryption as well as the encryption of files on network or shared drives. The encryption of shared files is among the doomsday scenarios an organization can imagine. It takes only one employee on the network to execute ransomware and affect the entire company.

Source: Cybereason Introduces: Free Behavioral-Based Ransomware Blocking

Interesting. Unfortunately Windows only.