CVE-2018-21055 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.0) (Qualcomm models using MSM8996 chipsets) software. A device can be rooted with a custom image to execute arbitrary scripts in the INIT context. The Samsung ID is SVE-2018-11940 (September 2018).
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Analysis
by VulDB Data Team • 10/07/2020
This vulnerability represents a critical security flaw in Samsung mobile devices running Android 7.0 with Qualcomm MSM8996 chipsets, specifically affecting the device's boot process and privilege escalation mechanisms. The issue stems from inadequate security controls during the initial system initialization phase, allowing malicious actors to gain root access through custom firmware images. The vulnerability exploits weaknesses in the bootloader and early boot environment where insufficient authentication mechanisms permit unauthorized code execution with the highest system privileges. This represents a fundamental breakdown in the device's security model, as the INIT context typically operates with system-level privileges and can execute arbitrary scripts with complete control over the device's functionality.
The technical implementation of this vulnerability involves manipulating the device's boot sequence to bypass standard security checks that would normally prevent unauthorized modifications. Attackers can flash custom images that exploit the trust relationship between the bootloader and the system components, effectively creating a backdoor that operates below the normal operating system layers. The vulnerability specifically targets the Qualcomm MSM8996 chipset architecture where the boot process lacks proper cryptographic verification of system components, allowing attackers to inject malicious code that executes with the same privileges as the system initialization process. This flaw operates at the kernel level and can be leveraged to establish persistent access to the device's core functionality.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the device's hardware and software environment. Once exploited, adversaries can install persistent malware, access all device data, monitor communications, and potentially use the compromised device as a staging point for further attacks. The vulnerability affects a significant number of Samsung devices from 2016-2017, creating a large attack surface for threat actors who can leverage this flaw for various malicious activities including data theft, surveillance, and establishing command and control channels. The security implications are particularly severe given that the vulnerability operates at the boot level, making detection and remediation extremely difficult.
Security mitigations for this vulnerability require immediate firmware updates from Samsung to address the bootloader security gaps and implement proper cryptographic verification of system components. Organizations should ensure all affected devices receive the latest security patches and consider implementing device management solutions that can monitor for unauthorized modifications. The vulnerability aligns with CWE-284 Access Control Issues and can be categorized under ATT&CK technique T1068, Local Privilege Escalation, as it allows attackers to gain elevated privileges through manipulation of the system boot process. Additionally, this flaw demonstrates weaknesses in the supply chain security model and highlights the importance of secure boot mechanisms in mobile device architectures, particularly for critical components like the bootloader and early boot environment that operate with elevated privileges.