Google’s Project Zero reports that memory safety vulnerabilities—security defects caused by subtle coding errors related to how a program accesses memory—have been "the standard for attacking software for the last few decades and it’s still how attackers are having success". Their analysis shows two thirds of 0-day exploits detected in the wild used memory corruption vulnerabilities. Despite substantial investments to improve memory-unsafe languages, those vulnerabilities continue to top the most commonly exploited vulnerability classes.

In this post, we share our perspective on memory safety in a comprehensive whitepaper. This paper delves into the data, challenges of tackling memory unsafety, and discusses possible approaches for achieving memory safety and their tradeoffs. We'll also highlight our commitments towards implementing several of the solutions outlined in the whitepaper, most recently with a $1,000,000 grant to the Rust Foundation, thereby advancing the development of a robust memory-safe ecosystem.

Why we’re publishing this now

2022 marked the 50th anniversary of memory safety vulnerabilities. Since then, memory safety risks have grown more obvious. Like others', Google's internal vulnerability data and research show that memory safety bugs are widespread and one of the leading causes of vulnerabilities in memory-unsafe codebases. Those vulnerabilities endanger end users, our industry, and the broader society. We're encouraged to see governments also taking this issue seriously, as with the U.S. Office of the National Cyber Director publication of a paper on the topic last week.

By sharing our insights and experiences, we hope to inspire the broader community and industry to adopt memory-safe practices and technologies, ultimately making technology safer.

Our perspective

At Google, we have decades of experience addressing, at scale, large classes of vulnerabilities that were once similarly prevalent as memory safety issues. Our approach, which we call “Safe Coding”, treats vulnerability-prone coding constructs  themselves as hazards (i.e., independently of, and in addition to, the vulnerability they might cause), and is centered around ensuring developers do not encounter such hazards during regular coding practice.

Based on this experience, we expect that high assurance memory safety can only be achieved via a Secure-by-Design approach centered around comprehensive adoption of languages with rigorous memory safety guarantees. As a consequence, we are considering a gradual transition towards memory-safe languages like Java, Go, and Rust.

Over the past decades, in addition to large Java and Go memory-safe codebases, Google has developed and accumulated hundreds of millions of lines of C++ code that is in active use and under active, ongoing development. This very large existing codebase results in significant challenges for a transition to memory safety:

• We see no realistic path for an evolution of C++ into a language with rigorous memory safety guarantees that include temporal safety.

• A large-scale rewrite of all existing C++ code into a different, memory-safe language appears very difficult and will likely remain impractical.

We consider it important to complement a transition to memory safe languages for new code and particularly at-risk components with safety improvements for existing C++ code, to the extent practicable. We believe that substantial improvements can be achieved through an incremental transition to a partially-memory-safe C++ language subset, augmented with hardware security features when available. For instance, see our work improving spatial safety in GCP's networking stack.

Our investments in memory-safe languages

We are actively investing in many of the solutions outlined in our whitepaper and in our response to the US Federal Government’s RFI on Open Source Software Security.

• Android has written several components in Rust over the last few years, leading to compelling security improvements. In Android’s Ultra-wideband (UWB) module, this has improved the security of the module while also reducing the memory usage and inter-procedural calls. 

• Chrome has started shipping some features in Rust; in one case, Chrome was able to move its QR code generator out of a sandbox by adopting a new memory-safe library written in Rust, leading to both better security and better performance.

• Google recently announced a $1,000,000 grant to the Rust foundation to enhance interoperability with C++ code. This will facilitate incremental adoption of Rust in existing memory-unsafe code bases, which will be key to enabling even more new development to occur in a memory-safe language. Relatedly, we are also working on addressing cross-language attacks that can occur when mixing Rust and C++ in the same binary.

• Google is investing in building the memory-safe open-source ecosystem through ISRG Prossimo and OpenSSF’s Alpha-Omega project. Back in 2021, we funded efforts to bring Rust to the Linux Kernel, which is now enabling us to write memory-safe drivers. This funding is also going towards providing alternatives or upgrades to key open-source libraries in a memory-safe language, such as providing a memory safe TLS implementation.

We know that memory safe languages will not address every security bug, but just as our efforts to eliminate XSS attacks through tooling showed, removing large classes of exploits both directly benefits consumers of software and allows us to move our focus to addressing further classes of security vulnerabilities.