researchers find an unfixable bug in EVERY ARM cpu

Summary

This video delves into a fascinating CPU vulnerability that exploits speculative execution and memory tagging in ARM architecture. The attack, reminiscent of Spectre and Meltdown, leverages cache invalidation to bypass security measures, allowing information leakage. The presenter, Ed, breaks down complex concepts like memory corruption, buffer overflows, and memory tagging, explaining how researchers have identified a method to leak memory tags within the V8 JavaScript engine sandbox, highlighting the intricacies of this advanced exploit.

Takeaways

• 💡 Computers can 'see' the future to some extent through speculative execution, which is a method used to predict and preload memory addresses to avoid cache misses.
• 🔍 The video discusses a memory corruption vulnerability that exploits CPU's speculative execution to bypass ARM's security architecture.
• 👤 The presenter, Ed, introduces the topic with a focus on cybersecurity and software security, encouraging viewers to subscribe for more content.
• 📚 The script mentions 'Smashing the Stack', a foundational paper on buffer overflows that have been a major source of hacks since the 1990s.
• 🛡️ ARM's chip architecture has implemented features like memory tagging in ARMv8 and ARMv9 to enhance security against memory corruption vulnerabilities.
• 🔑 Memory tagging involves adding a specific number or tag to a pointer, which the CPU checks to ensure it matches metadata on each load and store operation.
• 🔄 The script explains how pointers work, including their role in virtual memory and how they are used to translate virtual memory addresses to physical memory addresses.
• 🚫 Memory tagging is designed to prevent attacks like use-after-free by recoloring freed memory addresses with different tags, causing exceptions if incorrectly accessed.
• 🕵️‍♂️ The researchers discovered a method to leak memory tags through speculative execution, which can undermine the security provided by memory tagging.
• 💻 The attack, named 'MTE Leak', operates within the V8 sandbox, which is used for running JavaScript, and the researchers found multiple 'TIC tag gadgets' that can be exploited.
• 🌐 The video concludes by emphasizing the complexity and significance of the paper, urging viewers to read the original research for a deeper understanding.

Q & A

What is the main topic of the video?

The main topic of the video is the discussion of a memory corruption vulnerability that allows bypassing a major feature of the ARM computer instruction set, which is related to memory tagging and speculative execution.

What are the two infamous bugs mentioned in the video that broke the internet around 2016-2017?

The two infamous bugs mentioned are Spectre and Meltdown, which are related to CPU vulnerabilities.

What is the purpose of memory tagging in ARM architecture?

Memory tagging in ARM architecture is a security feature that adds a specific number or tag to a pointer to prevent memory corruption attacks. If the tag is altered, the CPU will crash at runtime.

How does a buffer overflow work in the context of memory corruption?

A buffer overflow occurs when data is written past the boundaries of a buffer, potentially overwriting adjacent memory locations such as the return pointer, which can allow an attacker to take control of the program flow.

What is a pointer in computer architecture?

A pointer in computer architecture is a variable that stores the memory address of another value or object. It is used as an index into tables, which is part of the virtual memory system.

What is speculative execution and why is it used?

Speculative execution is a technique where the CPU predicts the path a program will take and preloads memory addresses into the cache to avoid cache misses and speed up execution.

How does the attack described in the video exploit speculative execution?

The attack exploits speculative execution by creating a guess pointer and a test pointer with the same memory tag. It then uses the speculative execution to check if the guessed tag is correct by timing whether the test pointer has been cached.

What is a cache invalidation side channel?

A cache invalidation side channel is a method used by attackers to leak information about the CPU's cache state, which can be used to infer the execution flow or data values.

What is a 'TIC tag gadget' mentioned in the video?

A 'TIC tag gadget' is a snippet of code that can be used to leak memory tags by exploiting speculative execution and cache invalidation side channels.

How did the researchers find TIC tag gadgets in the V8 VM?

The researchers identified TIC tag gadgets in the V8 VM by looking for code snippets that perform speculative execution and cache checks, which can be used to leak ARM V8 tags.

What is the significance of the attack being able to bypass hardware memory protection?

The significance is that it demonstrates a sophisticated method of exploiting CPU vulnerabilities, even within hardware-enforced security measures like ARM's memory tagging, to potentially execute memory corruption attacks.