1) Ignorance: those that says that the ignorance is happiness then never had a website or a servant that was hackeado. The problems of security concerning software and certain applications Web are very spread so that people are abreast of them. It always remembers to inform to you on the matter and it investigates everything what is necessary.
2) Uncertain local PC: it seems strange to think that your PC can affect an external servant, but the certain thing is that it is a fault of quite common security. If your you are the one who administers a website, then the possibility exists. If somebody desire access to your computer, can gain access to your Web. To maintain your safe PC is very important.
3) Data to center of low security: in this case we did not speak of firewalls. What type of access has the data to center where lodge the servers in which hostea your Web? Account with cameras of security and doors that require cards? Or can somebody simply enter as if its house outside?
4) User X: this user is the one that no company would wish to have. This type of person is present in almost all the companies and is that one whose password is 123456 and that does not update its computer from the past century. These people usually are a weakness, so you must fortify it or clear it of in the middle.
5) Fax machines: it can seem strange, but cases in that exist documents of very high importance are sent by fax, and if that fax is within reach of anyone, then somebody could take a document from important without you find out.