The point of a methodology is to be able to produce interesting and significant results. If you've managed to apply some combination of existing methodologies to discover something interesting and new, then that discovery is likely publishable.
What is not clear, however, is whether a community of researchers who are focused on making new methodologies will be interested. Thus, you might not be able to publish in the particular machine learning community that you are interested in. Instead, I would suggest:
- Look for "applications" journals, conferences, or tracks associated with the machine learning community. Many "tool" communities have these associated: for example, in the general AI world, the core conference AAAI is always co-located with the much smaller but still high-significance IAAI applications meeting.
- Embrace the application community (it sounds like network security in this case), and publish your results there. They will be less interested in the methodologies and more in what you have done with them.