Running file gt00.7z confirms it is a 7-zip archive data.
Crack the hash using a wordlist: john --wordlist=rockyou.txt gt_hash.txt gt00.7z
strings gt00.7z | head -n 20 might reveal metadata or hints left by the creator. Running file gt00
Check the file for any trailing hidden data using binwalk -e . Conclusion gt00.7z