As many as 10 million users of VISA and MasterCard may have had their card numbers compromised in what sources in the financial sector are calling a “massive” breach of a U.S.-based credit card processor. Security experts focus anew on the good and bad of Payment Card Industry Data Security Standard. The breach shows that credit card data is still vulnerable three years after the Heartland Payment Systems breach of 130 million credit card numbers. The weak link today is not necessarily the technology, but “Layer 8,” the human layer.”]