In the age of smartphones, security vulnerabilities in the firmware of widely used devices like Google Pixel are particularly concerning. One such vulnerability is CVE-2022-42498, which made headlines because it could allow a remote attacker to execute code without any interaction from the user. In this post, we’ll break down what this flaw is, how it works, how it could be exploited, and how you can protect your device.

What is CVE-2022-42498?

CVE-2022-42498 is a security bug in certain versions of the Pixel cellular firmware. This bug is classified as an "out-of-bounds write," which means that an attacker can make the system write data where it shouldn't—outside the limits of the designated memory buffer. This can cause the device to behave in unsafe ways, including potentially running malicious code.

Key Details:

Product: Android Pixel devices (cellular firmware)

- Affected Component: Android Kernel / Cellular firmware  
- Android Tracking ID: A-240662453  
- References: No public technical advisory; see AOSP

How Does it Work?

At the core, this vulnerability exists because the cellular firmware did not check if data it's about to write would fit inside a specific buffer (a chunk of memory set aside for storing data). If too much data is sent, the device simply writes past the end – this is what we mean by "out-of-bounds."

Here’s a simplified snippet that shows the kind of problem we’re talking about

// Hypothetical vulnerable code
void handle_incoming_data(char *data, int len) {
    char buffer[256];
    // Missing: if (len > 256) { /* error handling */ }
    memcpy(buffer, data, len); // Uh oh – len can be larger than buffer!
}

With no size check, an attacker could send a specially crafted data packet that overflows the buffer. This lets them overwrite parts of memory they shouldn't be able to touch, possibly hijacking the execution of the device.

Possible Exploit Scenario

An attacker crafts a malicious cellular (radio layer) packet and sends it to a Pixel device—this could come from a rogue cell tower (also known as a fake base station). Since the device doesn’t validate the packet size, the attacker can overwrite important code in memory and make the device execute arbitrary commands. Since this runs in the baseband (modem) firmware, there’s no need for user permission or for the user to interact with the phone at all. The phone could be compromised without the user ever noticing.

Find a buffer in the modem firmware that is accessible over the air interface (radio).

2. Send a crafted radio packet to the device, making sure the payload is larger than the expected buffer size.

Redirect execution to attacker-controlled shellcode within the corrupted memory.

5. Gain code execution inside the modem, often allowing full control over the device's cellular radio—and sometimes the whole device.

Note: Because most modem firmware is proprietary and closed source, real-world exploits require skill and patience to discover the right memory regions and to craft stable shellcode. However, this vulnerability makes it *possible* for a remote attacker to eventually succeed.

Why Is This Dangerous?

- Invisible / Silent Attacks: No user interaction needed. Just being in the wrong place (within range of a malicious base station) is enough.
- Privilege Escalation: Attackers could use control over the modem to further attack the main Android OS, possibly accessing calls, texts, or even bypassing Android’s security model.
- Hard to Patch: Unlike regular apps, firmware updates are rolled out less frequently and are harder for the average user to apply.

Keep Your Pixel Updated: Google releases monthly security patches—always apply them.

2. Avoid Suspicious Networks: If possible, avoid connecting to unmanaged or unofficial networks, especially in high-risk regions.
3. Enable Automatic Updates: Make sure system and firmware updates are set to download/install automatically.
4. Monitor Official Security Advisories: Check with Google’s Pixel Security Bulletin for the latest information.

References

- Security Bulletin: Android – June 2022
- Android Open Source Project – Issue A-240662453
- OWASP: Buffer Overflow
- Pixel Security Updates

Conclusion

CVE-2022-42498 is a stark reminder that even the most modern devices can hide dangerous vulnerabilities—not just in their apps or OS, but also deep down in their firmware. Google has patched this issue in later firmware releases, but until every device is updated, those out in the wild remain exposed. Stay updated, stay alert!

*If you’re a developer or security researcher, remember to always check for proper bounds in your code. One missing check can open the door to a world of trouble.*

Timeline

Published on: 03/24/2023 20:15:00 UTC
Last modified on: 03/28/2023 19:18:00 UTC