Nikos Vasilakis

Rem Yang, Julian Dai, Nikos Vasilakis et al.

We assess how the code reasoning abilities of large language models (LLMs) generalize to different kinds of programs. We present techniques for obtaining in- and out-of-distribution programs with different characteristics: code sampled from a domain-specific language, code automatically generated by an LLM, code collected from competitive programming contests, and mutated versions of these programs. We also present an experimental methodology for evaluating LLM generalization by comparing their performance on these programs. We perform an extensive evaluation across 10 state-of-the-art models from the past year, obtaining insights into their generalization capabilities over time and across different classes of programs. Our results highlight that while earlier models exhibit behavior consistent with pattern matching, the latest models exhibit strong generalization abilities on code reasoning.

Nikos Vasilakis, Cristian-Alexandru Staicu, Grigoris Ntousakis et al.

Third-party libraries ease the development of large-scale software systems. However, they often execute with significantly more privilege than needed to complete their task. This additional privilege is often exploited at runtime via dynamic compromise, even when these libraries are not actively malicious. Mir addresses this problem by introducing a fine-grained read-write-execute (RWX) permission model at the boundaries of libraries. Every field of an imported library is governed by a set of permissions, which developers can express when importing libraries. To enforce these permissions during program execution, Mir transforms libraries and their context to add runtime checks. As permissions can overwhelm developers, Mir's permission inference generates default permissions by analyzing how libraries are used by their consumers. Applied to 50 popular libraries, Mir's prototype for JavaScript demonstrates that the RWX permission model combines simplicity with power: it is simple enough to automatically infer 99.33% of required permissions, it is expressive enough to defend against 16 real threats, it is efficient enough to be usable in practice (1.93% overhead), and it enables a novel quantification of privilege reduction.