An Input Flow Model Based Method for Software Security Design

摘要

An evil input may pose a serious threat to software security. In order to prevent such input based attacks as buffer overruns attacks, SQL injection attacks, an input flow model and a method for modeling is proposed as a way to design secure software using an object oriented approach. A source-destination relationship for input flow between two classes and the concept of affected range for input are defined. A new diagram, named Input Flow Diagram, is extended to UML. This diagram precisely describes the range that is affected by input. Based on this diagram, a firewall technique is proposed for designing a secure software system. A firewall acts as the boundary between untrustworthy and trusted classes. By using the firewall, all inputs are guaranteed to be validated before they cross this boundary, so the threats of evil inputs are prevented, resulting a secure software system.