Shill: A Secure Shell Scripting Language

Speaker: Prof. Stephen Chong , Harvard University

Date: Wednesday, November 20, 2013

Time: 4:00 PM to 5:00 PM Note: all times are in the Eastern Time Zone

Refreshments: 4:00 PM

Public: Yes

Location: G882

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Host: Raluca Ada Popa, MIT CSAIL

Contact: Raluca Ada Popa, raluca@csail.mit.edu

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Reminders to: seminars@csail.mit.edu

Reminder Subject: TALK: Shill: A Secure Shell Scripting Language

Speaker: Prof. Stephen Chong, Harvard University

Abstract: Reasoning about the security of shell scripts is notoriously hard: it is difficult for programmers to deduce the effects of shell scripts on the underlying operating system. First, resource references, such as file paths, are typically resolved lazily and subject to race conditions. Second, shell scripts are typically run with the same privileges as the invoking user, making it hard to determine or enforce that a script has all (and only) permissions to execute successfully. Third, shell scripts invoke other programs, often arbitrary binaries.

In this talk, I present the preliminary design and implementation of Shill, a new secure shell scripting language that uses fine-grained capabilities to restrict access to resources. Capabilities bind resources at the time of their creation, and avoid vulnerabilities arising from lazy name resolution. Shill scripts come with a declarative interface that specifies and restricts which capabilities the script may use. A Shill script can invoke an arbitrary binary in a sandbox that limits the privileges of the binary based on a set of capabilities. Capabilities together with declarative interfaces and sandboxing enable the caller of a script to reason precisely about which resources a script (and the binaries it calls) may access, and thus, Shill helps reason safely and effectively about the use and composition of scripts. We have implemented Shill on top of FreeBSD, using Racket and the FreeBSD Trusted MAC framework.

Bio: Steve Chong is a Computer Science faculty member in the Harvard School of Engineering and Applied Sciences. Steve's research focuses on programming languages, information security, and the intersection of these two areas. He is the recipient of an NSF CAREER award, and an AFOSR Young Investigator award. He received a PhD from Cornell University, and a bachelor's degree from Victoria University of Wellington, New Zealand.

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Created by Raluca Ada Popa Email at Monday, November 18, 2013 at 3:29 PM.