Devils in the Guidance: Predicting Logic Vulnerabilities in Payment Syndication Services through Automated Documentation Analysis

Finding logic flaws today relies on the program analysis that leverages the functionality information reported in the program's documentation. Our research, however, shows that the documentation alone may already contain information for predicting the presence of some logic flaws, even before the code is analyzed. Our first step on this direction focuses on emerging syndication services that facilitate integration of multiple payment services (e.g., Alipay, Wechat Pay, PayPal, etc.) into merchant systems. We look at whether a syndication service will cause some security requirements (e.g., checking payment against price) to become unenforceable due to losing visibility of some key parameters (e.g., payment, price) to the parties involved in the syndication, or bring in implementation errors when required security checks fail to be communicated to the developer. For this purpose, we developed a suite of Natural Language Processing techniques that enables automatic inspection of the syndication developer's guide, based upon the payment models and security requirements from the payment service. Our approach is found to be effective in identifying these potential problems from the guide, and leads to the discovery of 5 new security-critical flaws in popular Chinese merchant systems that can cause circumvention of payment once exploited.