Not only do we in the Comodo community think that default deny is one of, if not the best option of an anti-malware solution, but now Microsoft is using it in Windows Defender Antivirus.
When Windows Defender Antivirus encounters a suspicious but undetected file, it queries our cloud protection backend. The cloud backend applies heuristics, machine learning, and automated analysis of the file to determine whether the files are malicious or clean.
In Windows 10, version 1803, block at first sight can now block non-portable executable files (such as JS, VBS, or macros) as well as executable files.
Block at first sight only uses the cloud protection backend for executable files and non-portable executable files that are downloaded from the Internet, or that originate from the Internet zone. A hash value of the .exe file is checked via the cloud backend to determine if this is a previously undetected file.
If the cloud backend is unable to make a determination, Windows Defender Antivirus locks the file and uploads a copy to the cloud. The cloud performs additional analysis to reach a determination before it either allows the file to run or blocks it in all future encounters, depending on whether it determines the file to be malicious or safe.
This combined with the new Windows 10 sandbox feature appears that Windows may in future move to enable running ‘undetected’ files in a sandbox.
It would appear Microsoft is certainly taking ideas from Comodo on the security front.