The DARPA grant covers a project named Assured Micropatching that will take four years to complete. Developers could push micro-updates to fix devices vulnerable to cyberattacks without replacing the entire firmware. If they succeed, fixing very old systems in the absence of the source code should be possible. While its an exciting proposition, it will take a long time to become commonplace, and that’s only true if they find a way to do it safely.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/darpa-invests-make-iot-micro-patching-reality/