CVE-2018-21076

Vulnerability

An information disclosure vulnerability exists in the Secure Driver of Samsung mobile devices with N(7.x) software and Exynos8890 or Exynos8895 chipsets. The bug allows a modified trustlet—a trusted application running in the secure world—to leak the kernel address space layout randomization (KASLR) offset from the Secure Driver. The affected versions are those with the N(7.x) firmware on the specified Exynos chipsets.

Exploitation

An attacker must be able to load a modified trustlet into the secure execution environment. This typically requires either physical access, a prior compromise of the secure world, or the ability to flash a malicious trustlet. Once the modified trustlet is executed, it exploits the vulnerability to extract the KASLR offset, which is normally hidden to protect kernel memory layout.

Impact

Successful exploitation results in disclosure of the KASLR offset, defeating kernel address space layout randomization. This information disclosure weakens the overall kernel security posture, making subsequent attacks (e.g., kernel memory corruption exploits) easier to execute. The attacker gains no direct code execution but obtains a critical piece of information for further exploitation.

Mitigation

Samsung addressed this issue in its April 2018 security update, as indicated by the Samsung ID SVE-2017-10987. Users should ensure their devices are running the latest firmware to receive the fix. No workaround is available for unpatched devices.