Crypto virii disguise themselves as various file formats, PDF, EXE, and others. We have seen a sharp increase in these types of viruses over the years. They are a type of ransomware, almost always leaving the infected computer and user with a total data loss.
If you notice any unusual activity on your PC, you should run a virus scan with Malwarebytes to insure the infection is removed.
It’s also very important to maintain cloud backups of your data seperate from your machine to protect your data from these viruses.