Many of today’s web applications are built on frameworks that include sophisticated defenses against malicious adversaries. However, mistakes in the way developers deploy those defenses could leave applications open to attack. To address this issue, we introduce Rubyx, a symbolic executor that we use to analyze Ruby-on-Rails web applications for security vulnerabilities. Rubyx specifications can easily be adapted to a variety of properties, since they are built from general assertions, assumptions, and object invariants. We show how to write Rubyx specifications to detect susceptibility to cross-site scripting and cross-site request forgery, insufficient authentication, leaks of secret information, insufficient access control, as well as application-specific security properties. We used Rubyx to check seven web applications from various sources against our specifications. We found many vulnerabilities, and each application was subject to at least one critical attack. Encouragingly, we also found that it was relatively easy to fix most vulnerabilities, and that Rubyx showed the absence of attacks after our fixes. Our results suggest that Rubyx is a promising new way to analyze Ruby-on-Rails web applications for security vulnerabilities. 1.

Flaws in the standard libraries of secure sandboxes represent a major security threat to billions of devices worldwide. The standard libraries are hard to secure because they frequently need to perform low-level operations that are forbidden in untrusted application code. Existing designs have a single, large trusted computing base that contains security checks at the boundaries between trusted and untrusted code. Unfortunately, flaws in the standard library often allow an attacker to escape the security protections of the sandbox. In this work, we construct a Python-based sandbox that has a small, security-isolated kernel. Using a mechanism called a security layer, we migrate privileged functionality into memory-safe code on top of the sandbox kernel while retaining isolation. For example, significant portions of module import, file I/O, serialization, and network communication routines can be provided in security layers. By moving these routines out of the kernel, we prevent attackers from leveraging bugs in these routines to evade sandbox containment. We demonstrate the effectiveness of our approach by studying past bugs in Java’s standard libraries and show that most of these bugs would likely be contained in our sandbox.

Many of today’s web applications are built on frameworks that include sophisticated defenses against malicious adversaries. However, mistakes in the way developers deploy those defenses could leave applications open to attack. To address this issue, we introduce Rubyx, a symbolic executor that we use to analyze Ruby-on-Rails web applications for security vulnerabilities. Rubyx specifications can easily be adapted to a variety of properties, since they are built from general assertions, assumptions, and object invariants. We show how to write Rubyx specifications to detect susceptibility to cross-site scripting and cross-site request forgery, insufficient authentication, leaks of secret information, insufficient access control, as well as application-specific security properties. We used Rubyx to check seven web applications from various sources against our specifications. We found many vulnerabilities, and each application was subject to at least one critical attack. Encouragingly, we also found that it was relatively easy to fix most vulnerabilities, and that Rubyx showed the absence of attacks after our fixes. Our results suggest that Rubyx is a promising new way to discover security vulnerabilities in Ruby-on-Rails web applications.