Google’s Project Zero team discovered severe 0-day vulnerabilities with the Samsung Exynos modems used on the Pixel 6 and 7, Samsung phones and wearables, and other devices that warrant disabling VoLTE and Wi-Fi calling until patched.
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Exynos modem vulnerabilities
Known for finding 0-days, Project Zero reported 18 vulnerabilities in Exynos modems in late 2022 and early 2023. Four of the vulnerabilities, including CVE-2023-24033, involve internet-to-baseband remote code execution (emphasis ours):
Tests conducted by Project Zero confirm that those four vulnerabilities allow an attacker to remotely compromise a phone at the baseband level with no user interaction, and require only that the attacker know the victim’s phone number. With limited additional research and development, we believe that skilled attackers would be able to quickly create an operational exploit to compromise affected devices silently and remotely.
Meanwhile, the other 14 vulnerabilities are considered not as severe as they “require either a malicious mobile network operator or an attacker with local access to the device.”
Project Zero is making a “policy exception to delay disclosure for the four vulnerabilities that allow for internet-to-baseband remote code execution.” This is “due to a very rare combination of level of access these vulnerabilities provide and the speed with which we believe a reliable operational exploit could be crafted.”
According to Samsung Semiconductor (January 2023), these are the affected chipsets: Exynos Modem 5123, Exynos Modem 5300, Exynos 980, Exynos 1080, and Exynos Auto T5123. Google compiled a list of likely affected products:
- Samsung Galaxy phones including those in the S22, M33, M13, M12, A71, A53, A33, A21, A13, A12, and A04 series
- Vivo phones including those in the S16, S15, S6, X70, X60, and X30 series
- Google Pixel 6 and 6 Pro, Pixel 6a, Pixel 7 and 7 Pro
- Any wearables that use the Exynos W920 chipset
- Any vehicles that use the Exynos Auto T5123 chipset
Besides the Pixel 6 (Exynos 5123) and 7 (Exynos 5300), this includes the S22, as well as the Galaxy Watch 4 and 5. On Pixel phones, the main CVE-2023-24033 vulnerability was fixed with the March 2023 security patch that rolled out on Monday but should have come a week earlier.
Turn off VoLTE and Wi-Fi calling
However, the Pixel 6, 6 Pro, and 6a have yet to see that March update and are currently vulnerable. Project Zero’s advice for those impacted follows:
Until security updates are available, users who wish to protect themselves from the baseband remote code execution vulnerabilities in Samsung’s Exynos chipsets can turn off Wi-Fi calling and Voice-over-LTE (VoLTE) in their device settings. Turning off these settings will remove the exploitation risk of these vulnerabilities.
According to an older Sprint/T-Mobile support article, “Google Pixel devices received software updates in 2021 that automatically enabled VoLTE and removed the toggle.” You can disable Wi-Fi calling on Pixel phones in Settings app > Network & internet > SIMs > Wi-Fi calling.
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