general question regarding possible infection

A false emergency update for firefox was downloaded on my system followed by a flurry of activity on the hard drive. Once I realized what was happening I executed a hard shut down and loaded a previous image I had made with Macrium Reflect.

My question is could the malware have altered my system in such a way that it would survive the loading of a clean full disk image? I have run the boot scan with Avast with addition signatures added, and scanned for rootkits etc with Malwarebytes with nothing detected.

maybe, maybe not?

Option >> https://forum.avast.com/index.php?topic=194892.0