Cyber attack attribution is not a smoking gun that will hold up in a court of law. Attribution is a way of checking the assumptions of our threat model against the real world and revise those assumptions accordingly. State sponsored state sponsored actors might both focus on attribution both state sponsored and financially motivated actors. Dont ignore the OWAS Top Ten to focus on zero-day attacks over the longest period of time to extract maximum intelligence from the most frequent one off opportunistic attacks by financially motivated state actors.”]
Source: https://blog.malwarebytes.com/101/2016/10/attribution-and-when-you-should-care-part-1/