Well, obviously, a professional network of raiders would have their spies in many locations and investigate any interesting--and potentially profitable--leads they heard about. Then, they could gradually infiltrate whatever organization they thought would be most productive and unnoticeably move into positions within those organizations that would give them access (preferably indirectly) to whatever files or switches they needed to access.
One UFO-researching organization was allegedly taken over by nonbelievers who simply flooded that organization, took over the elections and controls, then were able to direct the meetings, website, etc
., the way they wanted it to go--away
from researching UFO reports. At least, that's the way some people described those events.
Also, I recently read that there were some suspicions that the German scientists allegedly "captured" by various nations at the end of World War II continued to perform their own, secret agenda, rather than assist the nations in which they were living. (That is, they may have done what the host-nation wanted, but also did their own activities.)
My infiltration-strategy mentioned above would be subtler and, presumably, draw no attention to its activities.