TC:Medium:Collaborative Research:Techniques to Retrofit Legacy Code with Security

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Though perhaps unfortunate, as a practical matter software is oftenbuilt with functionality as a primary goal, and security features areonly added later, often after vulnerabilities have been identified.To reduce the cost and increase assurance in the process of securityretrofitting, the aim to develop a methodology involving automated andsemi-automated tools and techniques to add authorization policyenforcement functionality to legacy software systems.The main insight is that major portions of the tasks involved inretrofitting code can be or already have been automated, so the designprocess focuses on enabling further automation and aggregating thesetasks into a single, coherent approach.More specifically, techniques and tools are being developed to: (1)identify and label security-relevant objects and I/O channels byanalyzing and instrumenting annotated application source code; (2)insert code to mediate access to labeled entities; (3) abstract theinserted checks into policy-relevant, security-sensitive operationsthat are authorized (or denied) by the application's security policy;(4) integrate the retrofitted legacy code with the site's specificpolicy at deployment time to ensure, through advanced policy analysis,that the application enforces that site's policy correctly, and (5)verify correct enforcement of OS policy delegation by the retrofittedapplication.The techniques and tools being developed are useful not onlyfor retrofitting, but also for augmenting and verifying existing codealready outfitted with security functionality; hence improving thestate-of-the-art in creating more secure software.