The .rar extension indicates that this is a Roshal Archive. The choice of RAR over the more common ZIP format is deliberate and offers several advantages for large software collections:
Files distributed under generic names like xf-2005-2021.rar are prime vectors for malware. Because users expect an executable file (.exe or .msi) inside the archive to install software, bad actors can easily embed trojans, keyloggers, or ransomware. xf-2005-2021.rar
: Specific versions require product keys to differentiate software sold as part of a suite versus individual products (e.g., AutoCAD 2021 uses key Academic Licenses bad actors can easily embed trojans
It sounds like you’re referencing a file named . xf-2005-2021.rar
"xf-2005-2021.rar" commonly associated with a collection of X-Force keygens