GZQUAR is a file extension used by antivirus software Bitdefender. GZQUAR files are generated by said software in order to store information about quarantined files.

Files that are perceived by Bitdefender as harmful to the system and for some reason cannot be deleted  are automatically placed into quarantine. Quarantined files isolated from system and cannot access any system resources due to being block for doing so by the antivirus applications.