Files with crk file extension can be found sometimes as crack files.
CRK file extension - Crack file
What is crk file? How to open crk files?
File type specification:
The crc file extension is mostly used for various "crack" files that are used to circumvent software protection. Usually a readme like file or data file associated with a special executable.
This crk file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.