I received DDOS because of the GD imageverification doesn't work!!!

[dragonlove]

Is there a problem in the vbulletin code that cause the GD library doesn't work?

My forum have this trouble, I can't ever see any image generated by the GD library , so I can't turn this option on and let people register without using this.

So after a few days I received many DDOS attack throught this :|

First I thought that the GD lib on the server has problem, and I installed an other vbulletin source, it run perfectly without this error!

Does any mod caused this?

I've installed these products :

Cyb - Advanced Forum Statistics 4.5
Cyb - Advanced Permissions Based on User's Post Count 3.8
Cyb - Forumhome Sub-Forums Manager 2.1
Cyb - Thread Listing Make-Up 1.1
Extra Image Verification 1.1
Fake Community Statistics 0.10
Fake Users 1.0.0
Members who have posted on the forum 4.38
Members who have read a thread. 3.33
Members who have visited the forum 4.41
nCode Image Resizer 1.0 RC 2
Nick's Forum Home Announcment 1.5
Post Thank You Hack 5.3
Top 'X' Stats by InfiniteWebby 1.2.1
vBadvanced CMPS 2.2.1 (vB 3.6)
vBShout

Or is there a shell the hackers installed into my vbulletin ???

Plz help me on this cauz now I need to close the registration but the forum is still needing members!

Thank you in advanced!