I always wondered how AWS/Amazon got away without the strong authentication. It turned out that they don't anymore in my case:
> Your card payment ending in XXXX failed when we attempted to charge it for AWS services on account YYYYYYYYYYYY because it requires additional authentication. To complete the payment, please complete your credit card authentication.
Expect an e-mail with subject "Action required – Your AWS account is past due" if you haven't gone through the authentication process for your card.
Luckily they were pretty noisy about it. I received the first mail about it on Dec 2nd and then reminders on Dec 6th, 9th and 13th. At this point I noticed it and made the payment. They didn't shut down any service meanwhile.