Upload the file to VirusTotal to scan it against 70+ antivirus engines. This is critical for generic "pack" files.
If the "pack" is only a few kilobytes but claims to be a large game mod, it is likely a shortcut to malware. pack 1203.rar
If the RAR asks for a password and directs you to a survey website to get it, it is a scam. Upload the file to VirusTotal to scan it
Inside the RAR, look for files named things like photo.jpg.exe . These are viruses disguised as images. pack 1203.rar