“An attacker just has to upload the binary, which won’t be detected by any anti-virus since it is legitimate and singed windows binary.”
Since July 2023, any user with a GitHub account can run code.exe tunnel and publish their machine to the web through Microsoft’s relay. The binary is signed by Microsoft, so antivirus waves it through. Microsoft’s documented fix is to block one domain, and that fails against a tunnel that was already set up once. Defenders have to block whole wildcard domains and write AppLocker rules to undo a feature Microsoft shipped on by default.