1.) First and foremost, you MUST always use your admincp renaming feature in your config.php. This is one of the most useful features that you could ever use. This prevents hackers from possibly spoofing or exploiting your login and seriously messing up your forums.

To do this, you must have FTP access. Go to your forum's directory and find your admincp folder. Right click on it and rename to anything you want. Remember the name because you will need it.

Next, you'll need to go to your Includes folder. Scroll down until you find your config.php. Open it with your favorite text editor and look for:

Replace admincp with whatever you named the folder, save, and upload.

You should do this with your modcp as well. Just follow the previous directions, except instead of renaming admincp, you'll want to rename modcp.

2.) Next, you'll want to password protect some directories. These directories include:

includes
install

If you have access to cPanel, you can password protect by using the "Password Protect Directories" option. Another way is to create a .htaccess.

You can follow this very helpful guide on how to do this : Password Protecting with .htaccess

However, keep this in mind... If you want any admins or mods to access their control panels for modding, they must know the passwords to the individual folders.

3.) Make yourself undeletable. To do this, edit your config.php again and search for:

You just type the userid of the user or users you want undeletable.

To find the userid of a user, just hover your mouse over their name on your forums, and you'll see "u=1" that number is their userid.

4.) An obvious one would be to keep your vBulletin and respectable mods updated at all times. This ensures that all the security flaws are kept to a minimum.

5.) Remove all respectable files from uninstalling mods.

6.) Do not allow HTML in anything, including posts, signatures, or PMs.

7.) Frequently check your computer malware, viruses, trojans, etc.

8.) Getting and using a reCaptcha system helps reduce and possibly prevent spammer registration.

9.) To further reduce or prevent spammer registration, you can add an extra question to registration using this guide.

10.) I've recently come across a new mod for vBulletin.. probably one of the best things I've ever seen. If you've ever run forums before and did a lookup on a suspicious IP, then you've most likely seen "StopForumSpam" Well, this mod works in colaberation with their list of known forum spammers with their normal emails, their IP addresses, and all the user names they've ever used. You can pick up this beautiful puppy here at vBulletin.com - vbStopForumSpam

These steps should help a lot in your prevention of hackers and spammers--or at least slow them down a bit.

If you have anymore information to provide, please reply and tell us about it!

Based on this source : Ultimate Guide to Securing your Forums