Visible to the public Biblio

Filters: Author is Nathan Fulton  [Clear All Filters]
2016-12-07
Nathan Fulton, Cyrus Omar, Jonathan Aldrich.  2014.  Statically typed string sanitation inside a python. PSP '14 Proceedings of the 2014 International Workshop on Privacy & Security in Programming.

Web applications must ultimately command systems like web browsers and database engines using strings. Strings derived from improperly sanitized user input can as a result be a vector for command injection attacks. In this paper, we introduce regular string types, which classify strings constrained statically to be in a regular language specified by a regular expression. Regular strings support standard string operations like concatenation and substitution, as well as safe coercions, so they can be used to implement, in an essentially conventional manner, the pieces of a web application or framework that handle strings arising from user input. Simple type annotations at function interfaces can be used to statically verify that sanitization has been performed correctly without introducing redundant run-time checks. We specify this type system first as a minimal typed lambda calculus, lambdaRS. To be practical, adopting a specialized type system like this should not require the adoption of a new programming language. Instead, we advocate for extensible type systems: new type system fragments like this should be implemented as libraries atop a mechanism that guarantees that they can be safely composed. We support this with two contributions. First, we specify a translation from lambdaRS to a calculus with only standard strings and regular expressions. Then, taking Python as a language with these constructs, we implement the type system together with the translation as a library using typy, an extensible static type system for Python.

2016-12-05
Nathan Fulton.  2012.  Domain Specific Security through Extensible Type Systems. SPLASH '12 Proceedings of the 3rd annual conference on Systems, programming, and applications: software for humanity. :107-108.

Researchers interested in security often wish to introduce new primitives into a language. Extensible languages hold promise in such scenarios, but only if the extension mechanism is sufficiently safe and expressive. This paper describes several modifications to an extensible language motivated by end-to-end security concerns.