[DefCon32] Sudos and Sudon’ts: Peering Inside Sudo for Windows
In a groundbreaking move, Microsoft introduced Sudo for Windows in February 2024, bringing a Unix-like privilege elevation mechanism to Windows 11 Insider Preview. Michael Torres, a security researcher at Google, delves into the architecture of this novel feature, exploring its implementation, inter-process communication, and potential vulnerabilities. Michael’s analysis, rooted in reverse engineering and Rust’s interaction with Windows APIs, uncovers security flaws that challenge the tool’s robustness. His open-source approach invites the community to scrutinize and enhance Sudo for Windows, ensuring it balances usability with security.
Understanding Sudo for Windows
Michael begins by demystifying Sudo for Windows, a utility designed to allow users to execute commands with elevated permissions directly from a non-elevated console. Unlike its Unix counterpart, it leverages User Account Control (UAC) for elevation and Advanced Local Procedure Call (ALPC) for communication between processes. Available in Windows 11 version 24H2, the tool supports three configurations: running commands in a new window, disabling input in the current window, or inline execution akin to Linux sudo. Michael highlights its open-source nature, hosted on GitHub, which enables researchers to dissect its codebase for potential weaknesses.
Security Implications and Rust Challenges
Delving into the technical intricacies, Michael examines how Sudo for Windows interoperates with Windows APIs through Rust, a language touted for memory safety. However, invoking native Windows APIs requires “unsafe” Rust code, introducing risks of memory corruption vulnerabilities—counterintuitive to Rust’s safety guarantees. He identifies non-critical issues reported to Microsoft’s Security Response Center (MSRC) and one embargoed vulnerability, emphasizing the need for rigorous scrutiny. For bug hunters, Michael advises focusing on unsafe Rust boundaries, where Windows API calls create exploitable seams.
Path Resolution and Process Coordination
Michael explores the path resolution process, critical for handling file and relative path inputs in Sudo for Windows. The tool’s reliance on ALPC for coordinating elevated and non-elevated processes introduces complexity, as it must maintain secure communication across privilege boundaries. Missteps in path handling or process elevation could lead to unintended escalations, a concern Michael flags for further investigation. His analysis underscores the delicate balance between functionality and security in this new feature.
Community Engagement and Future Directions
Encouraging community involvement, Michael praises the open-source release, urging researchers to probe the codebase for additional vulnerabilities. As Sudo for Windows rolls out to mainline Windows 11, its adoption could reshape administrative workflows, but only if security holds. He advocates for responsible bug hunting to prevent malicious exploitation, ensuring the tool delivers on its promise of seamless elevation without compromising system integrity.