“Agents, effects, and how toprotect yourself against them”

Effectful scripts—i.e., scripts that perform actions that change the world around them, such as modifying files in the file system or configuring a cloud deployment—are ubiquitous in computing. In addition to being ubiquitous, these scripts are very powerful since their effects are often irreversible or costly, and therefore getting them right is critical. Unfortunately, the state of the art in checking the correctness of effectful scripts lags far behind that of other programming domains, leading to the frequent occurence of high-impact bugs, such as accidentally deleting important user data. To make matters worse, these scripts are increasingly being implemented by agents in response to user prompts, where it is even harder to determine whether they are doing the right thing, since user intent is ambiguously hidden behind a natural-language prompt, and agents have been shown to hallucinate and to be vulnerable to prompt injections and other attacks.

In this talk, I will discuss three systems that we are developing to address this exact problem: how can we know whether an effectful script is doing what we want it to do, and how can we protect ourselves when it is not? First, I will talk about Sash, the first system for semantic analysis of shell scripts that can identify critical bugs, such as accidentally deleting the user’s home directory. Second, I will talk about try, a lightweight and easy-to-use system that allows transparently reverting a command’s effects on the file system. Third, I will talk about Caruca, a system that can automatically infer partial specifications of arbitrary black-box commands. Together, these systems can improve users’ confidence that the scripts they (or their agents) implement behave as intended.

Konstantinos Kallas is an assistant professor of CS at the University of California, Los Angeles. He is interested in building systems that enable the development of high-performance applications with robust correctness guarantees, both in theory and in practice. His research spans several domains, from serverless and microservices to the Unix shell and scripting languages in general, has appeared at several venues including SOSP, OSDI, NSDI, EuroSys, ATC, POPL, OOPSLA, and VLDB, and has received several awards (Dennis M. Ritchie SIGOPS 2024 dissertation award, best paper awards at OSDI 26, USENIX ATC 25, and EuroSys 21, best presentation at HotOS 21, and 2nd place at the 2021 ACM SRC Grand Finals). His research has led to the development of PaSh, the first optimizing compiler for the shell, which is supported by the Linux Foundation.