So, recovering from being hacked questions

[Keesa]

We were recently hacked. To resolve the issue some of the templates and pages in our vBulletin had to be pulled down.

Some were pages related to Mods, others were things as simple as an added page to vBulletin with outgoing links.

My questions are these:
How does one know if a Modification can increase the chances of being hacked?
If our forum, because of our topic, is subject to being targeted for hacking again, should we refrain from using ANY Modifications at all?

Or is it just dumb luck that the hacker got in and the files that they planted their evil code on were just chance?

If there are particular templates that the hacker got, does it mean THOSE modifications are how they got in?

There are a couple of Mods that are like water in a starving desert and I really really want to put them back in, and would be willing to give up others to keep them, but I do not want to put the forum at risk.

So, can someone help me understand?

Is the only safe forum a completely UNmodifed one? Well, safer forum? I imagine none are safe.