Files with crab file extension can be lately found as renamed encrypted archives affected by GandCrab ransomware.
CRAB file extension - GandCrab ransomware affected data
What is crab file? How to open crab files?
File type specification:
The crab file extension is most recently related to a new ransomware labeled as GandCrab. Much like similar ransomware it encrypts users files and demands ransom to be paid in bitcoins.
It also leaves instructions and ransom demands in a special text file "CRAB-DECRYPT.txt" file found in affected folders.