CVE-2014-4325 in Little Kernel Bootloader
Summary
by MITRE
The cmd_boot function in app/aboot/aboot.c in the Little Kernel (LK) bootloader, as distributed with Qualcomm Innovation Center (QuIC) Android contributions for MSM devices and other products, allows attackers to bypass intended device-lock and kernel-signature restrictions by using fastboot mode in a boot command for an arbitrary kernel image.
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Analysis
by VulDB Data Team • 03/05/2018
The vulnerability described in CVE-2014-4325 resides within the Little Kernel (LK) bootloader implementation, specifically in the cmd_boot function located in app/aboot/aboot.c. This bootloader serves as a critical first-stage component in Qualcomm MSM devices and other products that utilize QuIC Android contributions. The flaw represents a significant security weakness that directly undermines the device's integrity protection mechanisms by allowing unauthorized kernel image execution. The vulnerability occurs during the boot process when the bootloader fails to properly validate kernel signatures and device lock status, creating an exploitable path for malicious actors to bypass security controls.
The technical implementation of this vulnerability stems from inadequate input validation within the cmd_boot function that processes boot commands received through fastboot mode. When an attacker sends a boot command containing an arbitrary kernel image through fastboot interface, the bootloader does not sufficiently verify whether the kernel image is properly signed or whether the device is locked. This failure to validate cryptographic signatures and device state creates a direct path for privilege escalation and arbitrary code execution. The vulnerability is particularly concerning because it operates at the bootloader level, meaning it can bypass all higher-level security mechanisms and operating system protections. The flaw essentially allows an attacker with physical access to the device to load and execute unsigned kernel code, effectively neutralizing the device's security posture.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration. Attackers can leverage this vulnerability to install rootkits, modify system binaries, or extract sensitive information from the device. The ability to bypass device lock restrictions means that even locked devices can be compromised, undermining the fundamental security model of mobile devices. This vulnerability particularly affects devices running Qualcomm MSM processors and those utilizing QuIC Android contributions, potentially impacting millions of Android devices. The exploitation requires only fastboot mode access, which is often enabled in development devices or can be accessed through physical means, making the attack surface relatively broad and accessible to various threat actors.
Mitigation strategies for CVE-2014-4325 should focus on both immediate patching and architectural improvements. Device manufacturers and security teams must ensure that all affected LK bootloader implementations receive the necessary code updates to properly validate kernel signatures and device lock status before executing boot commands. The fix should implement robust cryptographic verification mechanisms that cannot be bypassed through fastboot mode commands. Additionally, security configurations should disable fastboot mode on production devices or implement strong authentication requirements for fastboot access. This vulnerability aligns with CWE-284 Access Control Bypass and maps to ATT&CK technique T1610 Exploitation of Remote Services, highlighting the need for comprehensive security controls at multiple layers. Organizations should also implement continuous monitoring for unauthorized bootloader modifications and establish secure boot processes that verify all components before execution. The remediation approach must address both the immediate vulnerability and strengthen overall bootloader security architecture to prevent similar flaws in future implementations.