Major challenge faced by known malwares is that after some time they start getting detected by static detection of Antiviruses. Resec Systems Red Team took one of a known malware which was getting detected by the AVs and made it fully undetectable by apply some custom algorithms to it. In this video demonstration, a POC is created which is able to bypass Windows Defender, McAfee Total Protection and BitDefender Total Security Antivirus.
Even though AV can be bypassed by threat actors but it is still advised to invest in a good Antivirus. Though threat actors comes with new techniques to bypass AVs but advanced behaviour based detection provided by AVs can mitigate such attacks.