CVE-2023-0705 - Understanding and Exploiting the Integer Overflow Vulnerability in Google Chrome Core

Google Chrome is one of the most widely used web browsers, making it a prime target for attackers. Sometimes, even small bugs can become dangerous if a skillful attacker triggers them in a specific way. One such bug, assigned as CVE-2023-0705, affected the browser’s core system and formed the basis for a low-severity yet intriguing security flaw. In this post, we’ll break down what this vulnerability is, how it can be exploited, and look at code examples to understand the risks involved—even though Chrome patched the issue in version 110..5481.77.

What Is CVE-2023-0705?

CVE-2023-0705 describes an integer overflow vulnerability within the Core module of Google Chrome. This bug allowed remote attackers to create a special kind of web page that, when visited, could potentially corrupt Chrome’s memory (specifically the heap) if they also managed to win a “race condition.”

Although the Chromium security team rated this as low severity (because it’s hard to trigger in practice), it’s an excellent case for learning about browser exploitation and memory safety.

Vulnerability summary

> Integer overflow in Core in Google Chrome prior to 110..5481.77 allowed a remote attacker who had won a race condition to potentially exploit heap corruption via a crafted HTML page. (Chromium security severity: Low)

The Technical Details

The core of the bug is that certain operations in Chrome’s core engine performed arithmetic (usually memory calculations) without checking for integer overflows. If an attacker could make specific values overflow during these calculations—and win a race in the browser's multi-threaded environment—they might get Chrome to allocate memory incorrectly, leading to a heap corruption.

Example Scenario

Imagine a situation where Chrome is allocating a buffer to handle user-supplied content on a web page:

size_t size = length * element_size;
// No check for overflow here!
void* buffer = malloc(size);

If length * element_size is bigger than the largest number the variable can store, a small value is calculated instead (due to overflow), and Chrome allocates a buffer that’s way too small. If Chrome then writes data into this buffer—thinking it’s much larger than it is—it corrupts heap memory.

Exploit Flow: How Could an Attacker Abuse This?

Even though winning a race condition and triggering an integer overflow at just the right time is hard, let’s see how an attacker might weaponize this:

1. Crafting the Malicious HTML

A web page is constructed to send weirdly large values (possibly via JavaScript arrays or typed arrays), trying to force the underlying allocation logic to overflow.

<script>
let arr = [];
for(let i=; i<100000; i++) {
    // Try to race memory allocation logic
    arr.push(new Uint8Array(xFFFFFFF)); // Large allocations
}
</script>

2. Trigger the Race Condition

Modern browsers use multiple threads for speed. The attacker tries to manipulate timing and thread execution using techniques like setTimeout, RequestAnimationFrame, or Web Workers.

// Example, simplified:
let shared = new SharedArrayBuffer(1024);
let worker = new Worker('worker.js');

worker.postMessage(shared);

// In worker.js:
onmessage = function(e) {
    let view = new Uint8Array(e.data);
    for (let i = ; i < view.length; i++) {
        view[i] = xFF;
    }
}

This can sometimes force two threads to access the same data at just the wrong moment, triggering the overflow.

3. Heap Corruption and Exploitation

If the attacker succeeds, they can make Chrome write out of bounds of an allocated buffer. This could crash the browser, but with a sophisticated technique, might allow code execution or data leakage (though Chrome’s sandbox and defenses make this very hard).

Severity: Low (hard to trigger, needs successful race)

- Possible Damage: Denial of Service (crash), potential for data leakage or controlled code execution if chained with other bugs

General Advice: Always keep your browser updated to get security patches!

- For Developers: Use safe integer arithmetic, add overflow checks, and avoid trusting user-supplied lengths and similar values.

References and Links

- Google Chrome Releases - Stable Channel Update for Desktop
- Chromium Issue Tracker (may require permission)
- CVE-2023-0705 on NVD
- Memory Safety in C++

Conclusion

CVE-2023-0705 is a classic demonstration of how even small mistakes in browser engines—especially those dealing with memory management—can have security implications, even if exploiting them in the real world is difficult. This vulnerability’s combination of integer overflow and race condition triggered a heap corruption risk, but Google’s prompt response and quick patching means users are protected—so long as they update their browsers!

Always keep your browser updated, and as a developer, remember to check your math—particularly when users control the numbers.


*This article is exclusive and written for educational purposes only. Do not attempt to exploit security vulnerabilities on systems you do not own or have permission to test.*

Timeline

Published on: 02/07/2023 21:15:00 UTC
Last modified on: 02/16/2023 14:59:00 UTC