Software Self-healing Using Error Virtualization

Stylianos Sidiroglou Software Self-healing Using Error Virtualization Despite considerable efforts in both research and development strategies, software errors and subsequent security vulnerabilities continue to be a significant problem for computer systems. The accepted wisdom is to approach the problem with a multitude of tools such as diligent software development strategies, dynamic bug finders and static analysis tools in an attempt to eliminate as many bugs as possible. Unfortunately, history has shown that it is very hard to achieve bug-free software. The situation is further exacerbated by the exorbitant cost of system down-time which some estimates place at six million dollars per hour. In the absence of perfect software, retrofitting error toleration and recovery techniques, in systems not designed to deal with failures, becomes a necessary complement to proactive approaches. Towards this goal, this dissertation introduces and evaluates a set of techniques for recovering program execution in the presence of faults by effectively retrofitting legacy applications with exception handling techniques, Error Virtualization and ASSURE . The main premise of the approach is that there is a mapping between faults that may occur during program execution and a finite set of errors that are explicitly handled by the program’s code. Experimental results are presented to support our hypothesis. The results demonstrate that our techniques can recover program execution in the case of failures in 80 to 90% of the examined cases, based on the technique used. Furthermore, the results illustrate that the performance overhead induced by the techniques to protect against a specific fault can be minimized to under 10%. This dissertation also describes two deployment mechanisms, Shadow Honeypots and Application Communities, that can reduce the cost of monitoring the application and, in turn, enable efficient deployment strategies for error virtualization systems.