Here is what I can tell you about managing a .rar file like "isus.rar":

If this file was unexpected, downloaded from an untrusted source, or arrived via email, it is highly recommended to scan it with an antivirus program before opening it.

"ISUS" sometimes refers to "InstallShield Update Service."

To give you the exact "feature" or information you need, could you tell me:

did you find "isus.rar" (e.g., inside a software folder, email attachment)?