Posted by Tim Willis, Project Zero

Note: 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.

In late 2022 and early 2023, Project Zero reported eighteen 0-day vulnerabilities in Exynos Modems produced by Samsung Semiconductor. The four most severe of these eighteen vulnerabilities (CVE-2023-24033 and three other vulnerabilities that have yet to be assigned CVE-IDs) allowed for Internet-to-baseband remote code execution. 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.

The fourteen other related vulnerabilities (CVE-2023-24072, CVE-2023-24073, CVE-2023-24074, CVE-2023-24075, CVE-2023-24076 and nine other vulnerabilities that are yet to be assigned CVE-IDs) were not as severe, as they require either a malicious mobile network operator or an attacker with local access to the device.

Affected devices

Samsung Semiconductor's advisories provide the list of Exynos chipsets that are affected by these vulnerabilities. Based on information from public websites that map chipsets to devices, affected products likely include:

• Mobile devices from Samsung, including those in the S22, M33, M13, M12, A71, A53, A33, A21, A13, A12 and A04 series;
• Mobile devices from Vivo, including those in the S16, S15, S6, X70, X60 and X30 series;
• The Pixel 6 and Pixel 7 series of devices from Google;
• any wearables that use the Exynos W920 chipset; and
• any vehicles that use the Exynos Auto T5123 chipset.

Patch timelines

We expect that patch timelines will vary per manufacturer (for example, affected Pixel devices have already received a fix for CVE-2023-24033 in the March 2023 security update). In the meantime, users with affected devices can protect themselves from the baseband remote code execution vulnerabilities mentioned in this post by turning off Wi-Fi calling and Voice-over-LTE (VoLTE) in their device settings. As always, we encourage end users to update their devices as soon as possible, to ensure that they are running the latest builds that fix both disclosed and undisclosed security vulnerabilities.

Four vulnerabilities being withheld from disclosure

Under our standard disclosure policy, Project Zero discloses security vulnerabilities to the public a set time after reporting them to a software or hardware vendor. In some rare cases where we have assessed attackers would benefit significantly more than defenders if a vulnerability was disclosed, we have made an exception to our policy and delayed disclosure of that vulnerability.

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, we have decided to make a policy exception to delay disclosure for the four vulnerabilities that allow for Internet-to-baseband remote code execution. We will continue our history of transparency by publicly sharing disclosure policy exceptions, and will add these issues to that list once they are all disclosed.

Related vulnerabilities not being withheld

Of the remaining fourteen vulnerabilities, we are disclosing five vulnerabilities (CVE-2023-24072, CVE-2023-24073, CVE-2023-24074, CVE-2023-24075 and CVE-2023-24076) that have exceeded Project Zero's standard 90-day deadline today. These issues have been publicly disclosed in our issue tracker, as they do not meet the high standard to be withheld from disclosure. The remaining nine vulnerabilities in this set have not yet hit their 90-day deadline, but will be publicly disclosed at that point if they are still unfixed.