Provide a means of automatically building yara rules

[jdheyburn]

Background

Typical usage of this module is build once, deploy once. And given that yara rules are compiled at build time, over time the lambda analyser that has been deployed will be out of date with new yara rules.

Desired Change

As an example implementation, we could deploy a lambda function that would periodically build the yara rules and store them in a location that the analyser lambda can retrieve them from to run the analyser against.