From what we've seen of security on the Enterprise-D, just about anyone could talk their way onboard ("Hi, I'd like to visit your impressive spaceship!"), waltz onto the bridge, shoot the entire bridge crew before they have time to respond, play a recording of Picard talking to the computer so you can lock out everyone not on the bridge, then take the turbolift to the shuttle bay, walk in, and simply fly off in a shuttle. The E-D is now flying on cruise control and most of the main cast is dead.
Alternately, you can take a tour of engineering, leave a time bomb in a hidden crevice next to the warp core, and then steal a shuttle. By the time they respond to your having stolen a shuttle, the warp core just got breached and the entire ship exploded.
A third option would be to just take out the main computer. If the ship doesn't go berserk and fly into a star while firing weapons at random and playing weird music over the intercom while futzing with the environmental controls, it will spontaneously explode.
You gotta wonder why the Klingons, Romulans, Dominion, Cardassians, etc. always insisted on shooting Federation starships when there were far easier methods of destroying them.
![Razz :P](./images/smilies/icon_razz.gif)
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