CVE-2019-20556 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with P(9.0) (SM6150, SM8150, SM8150_FUSION, exynos7885, exynos9610, and exynos9820 chipsets) software. RKP memory corruption allows attackers to control the effective address in EL2. The Samsung ID is SVE-2019-15221 (October 2019).
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Analysis
by VulDB Data Team • 10/04/2020
This vulnerability exists within Samsung's mobile device firmware targeting specific hardware chipsets including the SM6150, SM8150, SM8150_FUSION, exynos7885, exynos9610, and exynos9820 processors running Android Pie version 9.0. The issue is classified as a memory corruption flaw within the RKP (Reduced Kernel Privilege) component which operates at the EL2 (Exception Level 2) privilege level in the ARM architecture. The vulnerability allows attackers to manipulate the effective address within the kernel's memory space, potentially enabling arbitrary code execution with elevated privileges. This represents a critical security flaw that undermines the fundamental security boundaries between user space and kernel space operations on these devices.
The technical exploitation of this vulnerability stems from improper memory management within the RKP subsystem which controls kernel privilege levels in the ARM architecture. When attackers can control the effective address in EL2, they gain the ability to redirect execution flow to malicious code within the kernel space. This memory corruption issue specifically affects the ARM TrustZone security architecture implementation on Samsung devices, where RKP serves as a critical component for maintaining secure kernel operations. The flaw enables attackers to bypass normal privilege checks and potentially escalate their privileges to full kernel access, making it particularly dangerous for mobile device security.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full device compromise. Attackers who successfully exploit this flaw could gain complete control over affected Samsung devices, enabling them to access sensitive user data, install malicious applications, modify system files, and potentially establish persistent backdoors. The vulnerability affects multiple high-end Samsung devices from the Galaxy S8, S9, and Note 8 series, making it particularly concerning given the widespread deployment of these models. This flaw represents a significant weakness in the ARM TrustZone security framework implementation and could allow for sophisticated attacks including mobile malware deployment, data exfiltration, and device tracking.
Mitigation strategies for this vulnerability should focus on immediate firmware updates from Samsung as the primary solution, since the flaw resides in the device's secure boot and kernel privilege management components. Organizations and users should implement device management policies requiring immediate patching of affected devices, particularly those in enterprise environments where mobile device security is paramount. The vulnerability demonstrates the critical importance of proper memory management in secure kernel components and highlights the need for thorough security testing of ARM TrustZone implementations. Security teams should monitor for any related attack vectors that might leverage this privilege escalation to develop comprehensive defensive strategies, while also considering the broader implications for mobile security architecture and the potential for similar flaws in other ARM-based secure execution environments.
This vulnerability aligns with CWE-121, which addresses stack buffer overflow conditions, and CWE-122, which covers heap buffer overflow conditions, as both relate to improper memory handling in kernel space. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers Exploitation for Privilege Escalation, and T1543, which addresses Create or Modify System Process. The Samsung security advisory SVE-2019-15221 indicates that this was addressed through firmware updates that corrected the memory corruption handling within the RKP subsystem, emphasizing the importance of timely security patches in mobile device environments where hardware-level security features are critical for overall system integrity.