While it could refer to a few different database systems, the guide below covers the most likely scenarios for extracting and restoring the data. To access the contents, you must first unzip the .7z file. How can I uncompress a *.7z file? - Ask Ubuntu
The file is a compressed archive that typically contains a backup of a Known Files Database (KFDB) . This format is most commonly associated with forensic software used to store hashsets of known files or high-performance database engines like Kickfire . KFDB-backup.7z