CVE-2019-20567 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.x), O(8.x), and P(9.0) (Exynos chipsets) software. A up_parm heap overflow leads to code execution in the bootloader. The Samsung ID is SVE-2019-14993 (September 2019).
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Analysis
by VulDB Data Team • 10/04/2020
This vulnerability represents a critical heap overflow condition affecting Samsung mobile devices equipped with Exynos chipsets running Android versions 7.x, 8.x, and 9.0. The flaw exists within the bootloader component of these devices, specifically in how the up_parm parameter is handled during memory allocation operations. The heap overflow occurs when the bootloader processes certain input parameters without proper bounds checking, allowing malicious actors to overwrite adjacent memory locations in the heap region. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, which represents a well-known and dangerous class of memory corruption flaws that can lead to arbitrary code execution. The vulnerability is particularly concerning because it operates at the bootloader level, which represents one of the most privileged execution environments in mobile devices, making it an ideal target for attackers seeking persistent system compromise.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the capability to bypass device security mechanisms and potentially gain root access to the entire system. The bootloader is responsible for initializing hardware components and loading the operating system, making it a prime target for attackers seeking to establish persistent backdoors or modify system behavior at the lowest level. Attackers could exploit this vulnerability to install malicious firmware modifications, disable security features, or create persistent access points that survive device reboots. The Samsung-specific identifier SVE-2019-14993 indicates that this vulnerability was recognized and addressed by Samsung as part of their security advisory process, though the timeframe of September 2019 suggests that devices remained vulnerable for several months after the discovery. This vulnerability aligns with ATT&CK technique T1068 which describes "Exploitation for Privilege Escalation" and T1542.001 which covers "Pre-OS Boot" attacks targeting bootloaders and firmware components.
The technical exploitation of this heap overflow requires precise control over memory layout and parameter manipulation to achieve reliable code execution. The vulnerability's location within the bootloader means that exploitation typically requires physical access to the device or the ability to deliver malicious payloads through device-specific attack vectors such as USB-based attacks or firmware update mechanisms. The Exynos chipset architecture adds additional complexity to exploitation attempts, as the memory management and security features implemented by Samsung's custom hardware components can either mitigate or exacerbate the vulnerability's impact. Security researchers have noted that such bootloader-level vulnerabilities are particularly dangerous because they can be exploited before the operating system has a chance to implement its security controls, making traditional software-based mitigations ineffective. Organizations and users should be aware that devices running affected Android versions with Exynos chipsets were at risk of being compromised through this specific vulnerability, which could potentially enable full device takeover and data exfiltration capabilities for attackers with sufficient technical knowledge and access to exploit the flaw.