Pierluigi Paganini November 09, 2022

Google Project Zero researchers reported that a surveillance vendor is using three Samsung phone zero-day exploits.

Google Project Zero disclosed three Samsung phone vulnerabilities, tracked as CVE-2021-25337, CVE-2021-25369 and CVE-2021-25370, that have been exploited by a surveillance company.

The three issues are:

• CVE-2021-25337: Improper access control in clipboard service in Samsung mobile devices prior to SMR Mar-2021 Release 1 allows untrusted applications to read or write certain local files.
• CVE-2021-25369: An improper access control vulnerability in sec_log file prior to SMR MAR-2021 Release 1 exposes sensitive kernel information to userspace.
• CVE-2021-25370: An incorrect implementation handling file descriptor in dpu driver prior to SMR Mar-2021 Release 1 results in memory corruption leading to kernel panic.

The researchers pointed out that the surveillance firm included in its spyware the exploits for these three vulnerabilities that were zero-day at the time of their exploitation.

“This in-the-wild exploit chain is a great example of different attack surfaces and “shape” than many of the Android exploits we’ve seen in the past. All three vulnerabilities in this chain were in the manufacturer’s custom components rather than in the AOSP platform or the Linux kernel.” reads the advisory published by Google Project Zero. “It’s also interesting to note that 2 out of the 3 vulnerabilities were logic and design vulnerabilities rather than memory safety.”

The surveillance vendor chained the above vulnerabilities to compromise the Samsung phones.

The TAG team only obtained a partial exploit chain for Samsung phones that were likely in the testing phase. The experts revealed that the sample is dated back late 2020.

“The chain merited further analysis because it is a 3 vulnerability chain where all 3 vulnerabilities are within Samsung custom components, including a vulnerability in a Java component.” reported the advisory.

The experts explained that the exploit sample targets Samsung phones running kernel 4.14.113 with the Exynos SOC. This specific SOCs is used by phones sold in the Europe and Africa. The exploit relies on both the Mali GPU driver and the DPU driver which are specific to the Exynos Samsung phones.

Samsung phones that were running kernel 4.14.113 in late 2020 include the S10, A50, and A51.

Google reported the vulnerabilities to Samsung immediately after their discovery in late 2020s, and the vendor addressed them in March 2021.

Google did not reveal the name of the surveillance vendor, it only highlighted similarities with other campaigns that targeted Android users is Italy and Kazakhstan.

Project Zero noted that the advisories published by Samsung for these issues do not mention their exploitation in-the-wild.

“Labeling when vulnerabilities are known to be exploited in-the-wild is important both for targeted users and for the security industry. When in-the-wild 0-days are not transparently disclosed, we are not able to use that information to further protect users, using patch analysis and variant analysis, to gain an understanding of what attackers already know.” concludes the report.

“The analysis of this exploit chain has provided us with new and important insights into how attackers are targeting Android devices. It highlights a need for more research into manufacturer specific components.”

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Pierluigi Paganini

(SecurityAffairs – hacking, zero-day)

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