Legal compliance, no malware.
Forums like MacRumors or specialized virtualization blogs often provide verified, clean ISO images created from official installers. How to Create a 64-Bit ISO from an Official DMG/PKG mac os x iso download 64 bit top
Compare the output to the official hash provided by the source. If they match, your ISO is authentic and uncorrupted. If they differ, delete the file and download from another trusted source. Legal compliance, no malware