Some packers, such as UPX or WinRAR, are self-extracting packages that include an unpacking technology that's shipped with the tool. As you may know, these tools are not created to hide any malicious traits, so some of them provide these unpacking features for both developers and end users.
In some cases, malware uses a commercial protector in an illegal way to protect its malware from reverse engineering and detection. In this case, you can even directly contact the protection provider to unprotect this piece of malware for your analysis.
