What Is Memory Safety?

Memory safety is a property of a programming language or runtime environment that prevents programs from accessing memory in unintended or invalid ways. It ensures that programs access only authorized memory areas and reduces the risk of memory safety vulnerabilities that attackers can exploit for malicious code execution.

Why memory safety matters

Memory safety matters as it helps prevent memory-related vulnerabilities, data corruption, and system crashes caused by improper memory management. By ensuring memory safety, developers can enhance the following aspects of your solution:

• Security by design. Security controls built into memory-safe languages help developers create secure software by design and minimize the need for additional protections later in the development process.
• A reduced attack surface. Since memory safety eliminates memory-related vulnerabilities, it helps significantly reduce the software’s attack surface and strengthen its overall security resilience.
• Reliability. Strong memory safety reduces software crashes, unexpected behavior, and security incidents, while increasing its stability.
• Improved software quality. Availability of compiler checks, runtime checks, and automatic memory management helps detect issues earlier and enhance code quality.

What are memory safety vulnerabilities?

Memory safety vulnerabilities are software defects that cause a program to access, allocate, deallocate, or interpret memory in unintended and unsafe ways. They typically occur in languages that require manual memory management and include the following examples:

A buffer overflow is caused by software writing more data into a buffer than it can hold. The excess data can overwrite adjacent memory, corrupt metadata, or modify control-flow information. Buffer overflows can result in application crashes and data corruption.

A use-after-free appears when a program continues to use a pointer to memory that was deallocated. This results in a dangling pointer that references invalid memory. Attackers may exploit this condition to corrupt data, cause unexpected behavior, or execute arbitrary code.

Data races occur when two or more threads access the same memory location concurrently, at least one of the accesses is a write operation, and the accesses are not properly synchronized. Data races can lead to undefined or unpredictable behavior, resulting in incorrect program execution, application instability, security vulnerabilities, and, in some cases, memory corruption.

An out-of-bounds read/write happens when a program reads or writes memory outside the intended bounds of an allocated buffer, array, or object. In case of an out-of-bounds read, a program reads data outside the valid limits of a buffer. This can expose sensitive data and cause software crashes. In case of an out-of-bounds write, an app writes data beyond or before the allocated buffer, corrupting adjacent memory and enabling arbitrary code execution.

A type confusion arises when an app allocates or initializes a resource (object, pointer, variable) as one type but later accesses it using an incompatible type. As a result, the program misinterprets the underlying memory layout, which can lead to memory corruption and out-of-bounds access.

Memory-safe programming languages

Memory-safe languages embed protection into their runtime or compiler, preventing developers from handling memory manually. Various agencies provide lists of recommended languages for software development, which we’ll now explore.

According to the National Institute of Standards and Technology (NIST), software development in a safer, more secure language or language subset can help entirely avoid the whole class of weaknesses. Their list includes:

Rust

Rust provides memory safety guarantees at compile time through its ownership, borrowing, and lifetime system. These mechanisms prevent memory vulnerabilities such as use-after-free and data races without relying on garbage collection.

Ada

Ada promotes memory safety through strong typing, range constraints, and extensive compile-time and run-time checks.

SPARK

SPARK is a subset of Ada. It inherits Ada’s memory safety capabilities and introduces additional restrictions and verification mechanisms. SPARK also supports a safe pointer facility based on the ownership mechanism.

The Cybersecurity and Infrastructure Security Agency (CISA) and the National Security Agency (NSA) published a joint guide on memory-safe languages, which lists the following languages for secure software development:

C#

C# runs on .NET, which provides automatic memory management through garbage collection, type safety, and array bounds checking. Although C# supports unsafe code blocks, developers can avoid using them in security-sensitive solutions.

Go (Golang)

Go’s garbage collector, automatic bounds checking, and strong static type system significantly reduce the risk of common memory safety vulnerabilities and many forms of invalid memory access.

Java

Java enforces memory safety through automatic garbage collection, strict compile-time and runtime type checking, and bytecode verification. The Java Virtual Machine validates code execution and prevents operations that could compromise memory integrity.

Python

Python ensures memory safety through automatic memory management, reference counting with garbage collection, runtime safety checks, and the absence of direct memory manipulations.

Swift

Swift uses Automatic Reference Counting to manage object lifetimes automatically and prevent access to deallocated memory. It also supports runtime bounds checking on arrays and other collections and incorporates additional safety features that help prevent common memory-related vulnerabilities.

How to ensure memory safety in software development

To build memory-safe software or enhance your existing software security and stability, your team should adopt these practices:

1. Use memory-safe languages to implement security by design

When planning to build software from scratch or extend the existing solution with new components, it’s essential to choose a memory-safe language to reduce or eliminate the need for manual memory management and the occurrence of memory-related vulnerabilities.

2. Perform static analysis and runtime checks

Developers can use static analysis tools and runtime verification mechanisms to identify potential memory safety violations. These tools, such as Coverity (Synopsys) or Infer (Meta), help detect unsafe memory operations early in the development lifecycle to promptly address them.

3. Minimize manual memory management

Reducing manual memory handling reduces the risk of memory-related vulnerabilities. Depending on the technology stack, the mechanisms may include using smart pointers, following RAII (Resource Acquisition Is Initialization) principles, or relying on garbage collection if possible.

4. Validate external input

It’s essential to validate all external input, including lengths, offsets, and indexes, to protect memory operations because attacker-controlled input often influences allocation sizes, copy operations, loop boundaries, and memory access patterns.

5. Use safe abstractions

Developers can hide unsafe memory operations behind well-designed APIs and abstractions that enforce ownership, lifetimes, bounds, initialization, and cleanup. Instead of working directly with raw pointers or manually managing memory, the developers can make the abstraction responsible for enforcing memory safety guarantees and preventing misuse.

How Apriorit can help you build memory-safe software

With 20+ years of experience in writing software using a variety of programming languages, Apriorit can assist your team with:

• Custom software development in memory-safe languages, such as Rust, C#, Go, Python, and Swift.
• Memory management and memory safety development services involving building new or improving existing memory-critical products, kernel and driver memory management, and IoT and embedded software memory optimization.
• Cybersecurity development services, including system programming, data protection, security testing and audit.