I just noticed a security risk with Adster and I have contacted their support about it so hopefully they will fix the problem. I won't go into details about the problem since it may give some hackers ideas. I wouldn't add all of your personal and billing information in their system if I were you. I noticed this today while purchasing a new ad placement on a site.
Ok then. If you save your credit card info on file and purchase a new ad all of your credit card information including the security code is displayed on the buy page. Someone with an automated password retrieval script could get someone's login and have access to all of their credit card information. If you have your credit card saved on file go and purchase an ad and before you submit payment you will see a page where your name, address, full credit card number, expiration date, and 3 - 4 digit security code is displayed. Usually sites that store credit card info like Newegg and Amazon only display the last four digits of the credit card number and expiration date. Adster displays everything needed to make a purchase with a simple login.