I have monitoring this thing for long. It is really becoming a headache now. It continuously consuming a lot of CPU and Mysql resources for no reason. Form Spam like wordpress comment spam, directory registration/submission spam, forum spam consumes around 33% of the total CPU usage of a day in one of Mellowhost’s old server according to my calculation a couple of minutes ago. This consumption is pretty huge and grows as the server grows.
For some reason due to the development of auto scripts installer like Softaculous and Fantastico, users tend to try each script and leave them unattended. This keeps leaving form exploits for the botnet attackers. A wordpress blog without akismet is potentially threatened to form spam attack. Most of the phpbb forums contains no protection at all on the initial installation. These let the auto bot spammers to post their links in unattended forums/blogs to gain backlinks from their perspective.
This is not eventually only harmful for the server in realtime but also threaten the reputation of the shared IP. I have been working to try to develop a protection server wide to stop these spammers, but every attempt seems inadequate.
In many cases, it is hard to control or check manually as resellers add users and the users add many addon domains. It grows almost everyday. It is advised for every user, not to keep unattended blog/forum/script. It is always better to add some “Captcha” in all sort of registration form. Nowadays, spammers have broken the Captchas as well. Some people have already started some solution called Random questions. But anyway, there should be something like verification in the registration and the comments shouldn’t be allowed without registration. You can also add the Akismet plugin which is available for almost all the blogs and forums. It drastically reduces the number of spam and acts pretty quickly.
Protecting form spam is not only good for the server, but also good for your sites reputation. If you are hosting an unattended blog script inside one of your main site, than it may receive a serious damage of reputation in SEO if the unattended blog is regularly spammed by malicious users. So, check now, if you have any unattended script inside a folder, you should probably double check and delete it if it is not essential or protect it from auto botnets.