They will not only detect existing viruses. AV software has used heuristics to detect viruses for decades, and more recently ML is being used. Microsoft has rea

They will not only detect existing viruses. AV software has used heuristics to detect viruses for decades, and more recently ML is being used. Microsoft has really been investing in Defender and Defender ATP recently and there have been several Twitter and blog posts about the successes their ML approach is yielding, including for new viruses.