CVE-2018-21076 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.x) (Exynos8890/8895 chipsets) software. There is information disclosure (a KASLR offset) in the Secure Driver via a modified trustlet. The Samsung ID is SVE-2017-10987 (April 2018).
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Analysis
by VulDB Data Team • 10/07/2020
This vulnerability exists within Samsung's mobile device firmware targeting the n7.x software versions running on Exynos8890 and 8895 chipsets. The issue manifests as an information disclosure flaw that specifically affects the Secure Driver component through manipulation of a modified trustlet. The vulnerability exposes a kernel address space layout randomization offset which represents a critical security weakness in the device's memory protection mechanisms. KASLR serves as a fundamental defense against exploitation by randomizing kernel memory addresses, making it significantly harder for attackers to predict memory locations during exploit development.
The technical flaw operates through a trustlet modification that allows unauthorized access to kernel memory layout information. Trustlets represent trusted applications running in the secure environment that should maintain strict isolation from untrusted components. When compromised, these trustlets can leak kernel addresses through the Secure Driver interface, effectively undermining the security boundary that separates secure and non-secure execution environments. This type of information disclosure directly relates to CWE-200, which addresses the exposure of sensitive information to an unauthorized actor. The vulnerability represents a failure in the secure element's memory management and access control mechanisms.
The operational impact of this vulnerability is substantial as it provides attackers with critical information needed for advanced exploitation techniques. The leaked KASLR offset enables sophisticated attacks that would otherwise require extensive reconnaissance to determine kernel memory layouts. Attackers can leverage this information to bypass kernel security protections, potentially leading to privilege escalation or complete system compromise. The vulnerability affects devices running on the Exynos8890 and 8895 chipsets, which represent a significant portion of Samsung's mobile device portfolio from that era. This disclosure creates opportunities for exploitation that align with techniques described in the attack tactics and techniques framework, particularly those involving privilege escalation and kernel exploitation.
The security implications extend beyond immediate exploitation as this information disclosure represents a foundational weakness in the device's security architecture. The vulnerability demonstrates a failure in the secure element's ability to maintain memory isolation and protect kernel memory layout information from unauthorized access. Organizations should implement immediate mitigations including firmware updates, secure element access controls, and monitoring for suspicious trustlet behavior. The vulnerability also highlights the importance of proper secure element management and the need for robust access controls within the trusted execution environment. Given that this vulnerability affects devices from 2018, proper patch management and device lifecycle management become critical factors in maintaining security posture. The exposure of kernel memory layout information through the Secure Driver interface represents a significant weakening of the device's overall security framework and requires comprehensive remediation strategies.