Richard Bejtlich outlines what can be done to determine what one sort of adversary (primarily the criminal underground) knows about your organization. Some of these approaches can really only be accomplished by law enforcement, or by collaboration with law enforcement. Even taking a step into the underground can be considered suspicious. It obviously could be extended elsewhere but that is not the focus of this post. None of these steps are new; you can review success stories posted by the FBI and other organizations to know they work. However, I post them here to reinforce that.”]
Source: https://taosecurity.blogspot.com/2009/06/counterintelligence-options-for-digital.html