Google launched the Pixel 9 series with some improvements compared to previous generations. While the new features and design stand out above everything else, there are also improvements at the security level. Google has revealed how it has enhanced security against modem or baseband attacks in the Pixel 9 series.
The importance of preventing modem-related vulnerabilities
Our smartphones have become an extension of ourselves. Protecting these devices from potential attacks is crucial as they store a significant amount of personal data. Google has worked hard to solve or mitigate vulnerabilities that may be present in Android. Although the most visible efforts are at the OS level, there are components, such as basebands, that require special treatment.
The baseband is part of the set of hardware and software that manages mobile signals on your device. The device’s baseband and modem work together to fulfill the tasks of sending/receiving and processing signals, respectively. When talking about vulnerabilities, many focus mainly on the OS or on apps. However, baseband firmware is a sensitive component whose nature makes it prone to certain types of external attacks, like phishing campaigns using false base stations.
Google had security issues with Exynos modems
Google has already had to deal with baseband vulnerabilities in Tensor chips. The company’s hardware inherited these vulnerabilities from the Exynos modems it relies on. Between late 2022 and early 2023, Google found and disclosed a modem vulnerability that “remotely compromises a phone at the baseband level with no user interaction.” At the time, the Mountain View giant advised users to disable VoLTE and Wi-Fi calling while they worked on a fix.
Additionally, baseband security is the responsibility of each Android brand. “Mature software hardening techniques that are commonplace in the Android operating system, for example, are often absent from cellular firmwares of many popular smartphones,” Google says in a blog post. Anyway, Android includes system-level protections for attacks arising from potential baseband vulnerabilities.
This is how Google “shielded” the Pixel 9 series’ modem against baseband vulnerabilities
The Pixel 9, Pixel 9 Pro, Pixel 9 Pro XL, and Pixel 9 Pro Fold use a new Exynos 5400 modem and baseband set. The modem is not only more efficient but also more secure. Google has built in multiple layers of security at the hardware level, on top of Android’s native security layers. First, “Bounds Sanitizer” prevents malicious code from running or memory corruption from data overflow techniques.
“Integer Overflow Sanitizer” is another of the security measures implemented by Google. The system ensures that calculations during data processing are accurate to prevent attackers from “confusing” the baseband with false values that cause unexpected behavior. “Stack Canaries” is a system that guarantees the correct flow of code execution. If any block of code tries to “circumvent” the correct order, the modem will receive an alert.
“Control Flow Integrity (CFI)” acts similarly to “Stack Canaries,” but focuses on the “paths” along which code is executed rather than the execution order. If the system detects code that attempts to deviate from set execution paths, it will reset the modem. Finally, “Auto-Initialize Stack Variables” prevents the leakage or manipulation of confidential data caused by code initialization errors.
