It's always bugged me that "Teh Futurez" would use so many paper charts to present a big military plan.
I guess Microsoft in general and PowerPoint slide decks in particular have been banned by galactic agreement and unanimity by the 23rd century.
You can't remotely "Hack Paper" via Remote Wired or Wireless Network Information over the Internet.
Some times old school is just more secure.
You have to be there in-person, recording the information for "The Plan" if you have any major "Big Military Plans".
At that point, it's FAR easier to secure the "Big Military Plans" since all info is limited to those in-attendence.
Their network communication devices & computing devices can be easily secured at that point.
Any infiltration via bugs or surreptitious recording devices can be easily checked for by security.
The only thing you can't easily account for is if somebody is a traitor, short of Psychic Scanning for loyalty.
At that point, the person must be a pre-programmed psychic turn-coat that is programmed to turn against you by a remote field agent with a trigger of some sort.
The person would need to be "Conciously Un-Aware" that they've been programmed to be a Traitor.
That's far harder to pull off since your top brass & strategists would generally be secured from getting "Psy-Opped".
Short of the person being a long-term plant by the enemy, it's very hard to pull off these long games.
You would be required to kidnap said person, Psychically manipulate them on a mental programming level, then release said person and integrate them into the enemies society and get them high-enough on the security rank / Command Staff.
Not Impossible as shown with Star Trek history, but very rare.
I can only think of 1x times that this has happened.
In DS9 that one Alien Lady was a Pre-Programmed Agent where she didn't know she worked for somebody else.
Her actual memories were backed up on hard data storage of some form.