fluxsec.red/ - Discover the project plan for building Sanctum, an open-source EDR in Rust. Learn about the features, milestones, and challenges in developing an effective EDR and AV system.
Sanctum is an experimental proof-of-concept EDR, designed to detect modern malware techniques, above and beyond the capabilities of antivirus.
Sanctum is going to be an EDR, built in Rust, designed to perform the job of both an antivirus (AV) and Endpoint Detection and Response (EDR). It is no small feat building an EDR, and I am somewhat anxious about the path ahead; but you have to start somewhere and I’m starting with a blog post. If nothing else, this series will help me convey my own development and learning, as well as keep me motivated to keep working on this - all too often with personal projects I start something and then jump to the next shiny thing I think of. If you are here to learn something, hopefully I can impart some knowledge through this process.
I plan to build this EDR also around offensive techniques I’m demonstrating for this blog, hopefully to show how certain attacks could be stopped or detected - or it may be I can’t figure out a way to stop the attack! Either way, it will be fun!
Project rework
Originally, I was going to write the Windows Kernel Driver in Rust, but the bar for Rust Windows Driver development seemed quite high. I then swapped to C, realised how much I missed Rust, and swapped back to Rust!
So this Windows Driver will be fully written in Rust, both the driver and usermode module.
Why Rust for driver development?
Traditionally, drivers have been written in C & C++. While it might seem significantly easier to write this project in C, as an avid Rust enthusiast, I found myself longing for Rust’s features and safety guarantees. Writing in C or C++ made me miss the modern tooling and expressive power that Rust provides.
Thanks to Rust’s ability to operate in embedded and kernel development environments through libcore no_std, and with Microsoft’s support for developing drivers in Rust, Rust comes up as an excellent candidate for a “safer” approach to driver development. I use “safer” in quotes because, despite Rust’s safety guarantees, we still need to interact with unsafe APIs within the operating system. However, Rust’s stringent compile-time checks and ownership model significantly reduce the likelihood of common programming errors & vulnerabilities. I saw a statistic somewhere recently that some funky Rust kernels or driver modules were only like 5% unsafe code, I much prefer the safety of that than writing something which is 100% unsafe!
With regards to safety, even top tier C programmers will make occasional mistakes in their code; I am not a top tier C programmer (far from it!), so for me, the guarantee of a safer driver is much more appealing! The runtime guarantees you get with a Rust program (i.e. no access violations, dangling pointers, use after free’s [unless in those limited unsafe scopes]) are welcomed. Rust really is a great language.
The Windows Driver Kit (WDK) crate ecosystem provides essential tools that make driver development in Rust more accessible. With these crates, we can easily manage heap memory and utilize familiar Rust idioms like println!(). The maintainers of these crates have done a fantastic job bridging the gap between Rust and Windows kernel development.
