Material editor - Apply global constant

Hello, currently I have imported some materials into Unreal Engine 4. The problem is, that the materials are very shiny, so I would like to reduce the secularity and metallic to 0, and set the roughness to 1. It can easily be achieved through the Material Editor (when you double-click on a material), where it works flawlessly, but I have almost over a thousand materials I would have to perform the exact same process with.

My question goes:
Can I somehow easen up this process?