Our paper “how to shop for free online” is getting some publicity recently, which I am happy about, although Shaz and I did not directly participate in any of the interviews due to a non-academic reason. I compiled some news articles below:
• Researchers find major flaws in online payment systems. CNN, April 13, 2011.
• Exploit-wielding boffins go on free online shopping binge — World’s biggest e-commerce sites wide open, Register, April 12, 2011
• Could criminals shop for free online? CNET, April 11, 2011
• Security Researchers Exploit Logic Flaws to Shop for Free Online, Network World, April 11, 2011
The paper talks about 9 logic bugs in a set of representative merchant apps that integrate third-party cashier services PayPal, Amazon Payments and Google Checkout. The shopper is assumed completely malicious, and thus can play tricks to tell slightly inconsistent stories to the merchant and the cashier. As a result, the cashier is not 100% sure about “how much”, “to whom”, or “for which order” the shopper should pay; the merchant is not 100% sure about “how much”, “to whom”, or “for which order” the shopper did pay.
All the above news articles only talk about the bugs. Another interesting study in the paper is in Section V, in which we used Poirot (developed by MSR Redmond’s RiSE group and MSR India) to measure the logic complexity of a checkout mechanism. If you are a professor/lecturer who needs a real-world example to show benefits of formal methods, I recommend you to check out our case study page. The page is designed as a homework to challenge your students.