In response to the discovery of the Poweliks malware, a new fileless malware that lives and works entirely out of your computer system's registry, Mark James, security specialist at ESET says:
“The registry has always been a "sacred" place both for the inexperienced computer user and the malware writer. It is the backbone of your computer operating system and holds all the information needed for programs to run and operate correctly.
We have had "Registry Cleaners" for years that claim to do lots of things to speed up your machine, however very little evidence exists that says the registry can actually slow your machine down. In this day of super-fast hardware and gigabytes of memory these problems are associated with poorly uninstalled applications or remnants of files that no longer exist on your computer, but now we actually have something bad that can exist in your registry, it does not create any files to be cleaned or identified. It's not all bad though, the initial file used to infect the registry can be identified and cleaned/deleted before it is executed, so your antivirus will still protect you once your vendor has all the information for detection.
It is good practice to have your antivirus software keep an eye on your registry for any unwanted changes and notify you accordingly. All your IT professionals will suck air through their teeth if you want to talk to them about the registry, it's like that sacred recipe for Grandmas rice pudding, everyone knows about it but very few really understands how its made.”