Defense Event

Towards Least Privilege Principle: Limiting Unintended Accesses in Software Systems

Beng Heng Ng

Friday, May 03, 2013
2:00pm - 4:00pm
3725 BBB

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About the Event

Adhering to the least privilege principle involves ensuring that only legitimate subjects have access rights to objects. Sometimes, this is hard because of permission irrevocability, changing security requirements, infeasibility of access control mechanisms, and permission creeps. If subjects turn rogue, the accesses can be abused. This thesis examines three scenarios where accesses are commonly abused and lead to security issues, and proposes solutions to detect, and where practical eliminate, unintended accesses through SEAL, DeGap, and Expose. Firstly, we examine abuses of email addresses, whose leakages are irreversible. Also, users can only hope that businesses requiring their email addresses for validating affiliations do not misuse them. SEAL uses semi-private aliases, which permits gradual and selective controls while providing privacy for affiliation validations. Secondly, access control mechanisms may be ineffective as subject roles change and administrative oversights lead to permission gaps, which should be removed expeditiously. Identifying permission gaps can be hard since another reference point besides granted permissions is often unavailable. DeGap uses logs to estimate the gaps while using a common logic for various system services. DeGap also recommends configuration changes towards reducing the gaps. Lastly, unintended software code re-use can lead to intellectual property thefts and license violations. Determining whether an application uses a library can be difficult. Compiler optimizations, function inlining, and lack of symbols make using syntactic methods a challenge, while pure semantic analysis is slow. Given a library and a set of applications, Expose combines syntactic and semantic analysis to achieve performance and high quality rankings of applications.

Additional Information

Sponsor(s): Atul Prakash

Open to: Public