CVE-2019-20542 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.1), O(8.x), and P(9.0) (Exynos chipsets) software. There is a stack overflow in the kernel driver. The Samsung ID is SVE-2019-15034 (November 2019).
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/04/2020
This vulnerability represents a critical stack overflow condition affecting Samsung mobile devices equipped with Exynos chipsets running Android versions 7.1, 8.x, and 9.0. The issue resides within the kernel driver component of the device firmware, specifically manifesting as a buffer overflow that occurs during kernel-level operations. The vulnerability was identified and tracked by Samsung under their internal security tracking system as SVE-2019-15034, with the disclosure occurring in November 2019. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent stack memory locations.
The technical implementation of this vulnerability exploits the kernel driver's failure to properly validate input parameters before processing them within kernel space. When maliciously crafted input data is passed to the affected kernel driver, it causes the stack buffer to overflow, potentially leading to arbitrary code execution at kernel privileges. The attack vector typically involves exploiting the kernel driver through user-space applications that interact with the vulnerable subsystem. This allows an attacker to manipulate the execution flow of the kernel by overwriting return addresses, function pointers, or other critical stack data structures. The vulnerability is particularly concerning because kernel-level exploits can bypass standard operating system security mechanisms and provide attackers with complete system compromise capabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it creates a persistent backdoor for attackers to maintain long-term access to affected devices. Once exploited, the attacker gains full kernel-level privileges, enabling them to access all system resources, extract sensitive data, modify system files, and potentially install persistent malware. The affected Exynos chipsets represent a significant portion of Samsung's mobile device portfolio during the specified time periods, making this vulnerability widespread across multiple device generations. The exploitation of such kernel-level vulnerabilities aligns with ATT&CK framework techniques categorized under privilege escalation and persistence, specifically targeting the kernel rootkit and kernel-mode rootkit tactics. The vulnerability's impact is compounded by the fact that it affects multiple Android versions simultaneously, suggesting a fundamental flaw in the driver implementation rather than a version-specific issue.
Mitigation strategies for this vulnerability should focus on immediate firmware updates from Samsung, as the company would have released security patches addressing the specific stack overflow condition. System administrators and device users must ensure all affected devices receive the latest security updates, particularly those containing kernel-level fixes. Additionally, implementing runtime protections such as stack canaries, address space layout randomization, and kernel address space layout randomization can provide defense-in-depth measures against exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel drivers and demonstrates the necessity of rigorous security testing for low-level system components. Organizations should also consider monitoring for suspicious kernel-level activities and implementing device management policies that enforce timely security updates. The incident underscores the critical need for secure coding practices in kernel space development, particularly emphasizing the importance of bounds checking and memory management validation to prevent similar vulnerabilities from emerging in future implementations.