Although most of them may be legitimate, there is a chance that one or more could be malicious. Therefore, you should take time to scan the RAR file, ensure it is clean before exposing your PC to the contents within. For example, in a RAR, if you expect to have a video, but you find a file with a .exe extension it is likely to be malware. RAR technology is excellent in compressing files, so you don't have to shun it. However, you must evaluate the payload present within a RAR archive.