Are you trying to a specific file you found, or are you developing a feature to handle RAR files in an app?
Generic names like "aaaaaaaaa.rar" are frequently flagged in security databases because they are common in automated botnet distributions or phishing attempts.
: A popular, simple choice for macOS users to handle various archive formats. 2. Malware Analysis & Security
If you have this file and need to see what is inside, you will need a file archiver that supports the .rar format.
: You can upload the file here to see if it contains known threats according to dozens of antivirus engines.