CVE-2014-0974 in Little Kernel Bootloader
Summary
by MITRE
The boot_linux_from_mmc 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, does not properly validate a certain address value, which allows attackers to write data to a controllable memory location by leveraging the ability to initiate an attempted boot of an arbitrary image.
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Analysis
by VulDB Data Team • 03/05/2018
The vulnerability identified as CVE-2014-0974 resides within the Little Kernel (LK) bootloader implementation, specifically in the boot_linux_from_mmc function located in app/aboot/aboot.c. This bootloader serves as a critical component in Qualcomm MSM devices and various Android products, functioning as the initial software layer that loads the operating system kernel. The flaw manifests in improper validation of address values during the boot process, creating a potential pathway for malicious actors to manipulate memory operations. The LK bootloader operates at a low level within the device's boot sequence, making it a prime target for attackers seeking to gain control over the device's execution flow. This vulnerability is particularly concerning because it exists in the foundational boot code that runs before the operating system loads, providing attackers with early access to system resources.
The technical flaw stems from insufficient input validation within the boot_linux_from_mmc function, where the address value used for memory operations is not properly verified before being utilized. Attackers can exploit this weakness by crafting malicious boot images that contain specially formatted address values, enabling them to write data to arbitrary memory locations. This memory corruption capability represents a fundamental breakdown in the bootloader's security model, as it allows for direct manipulation of the device's memory space without proper authorization checks. The vulnerability essentially creates a write-what-where primitive that can be leveraged to overwrite critical bootloader components, system memory regions, or even kernel code. This type of flaw aligns with CWE-129, which describes improper validation of input ranges, and demonstrates how inadequate address validation can lead to memory corruption vulnerabilities.
The operational impact of this vulnerability extends beyond simple memory manipulation, as it provides attackers with a potential pathway to achieve code execution within the bootloader environment. Since the LK bootloader operates before the OS kernel loads, successful exploitation could allow attackers to modify the boot process itself, potentially enabling persistent backdoors or complete system compromise. The ability to write to controllable memory locations means that attackers could overwrite critical bootloader functions, modify boot parameters, or even replace the bootloader with malicious code. This vulnerability is particularly dangerous in mobile device contexts where the bootloader controls the entire boot chain and can influence the security posture of the entire system. The attack vector requires an attacker to be able to initiate a boot of an arbitrary image, which could be achieved through various means including physical access to the device or exploitation of other vulnerabilities in the device's update or recovery mechanisms.
Mitigation strategies for CVE-2014-0974 should focus on implementing proper address validation within the boot_linux_from_mmc function and other similar bootloader components. The most effective approach involves adding comprehensive input validation checks that verify address ranges and ensure that memory operations occur within legitimate boundaries. Security patches should enforce strict bounds checking on all address values used during the boot process, particularly those that control memory writes. Organizations should also implement secure boot mechanisms that verify the integrity of boot images before allowing them to execute, preventing unauthorized modifications from taking effect. Additionally, the vulnerability highlights the importance of proper code review and security testing of bootloader components, as these low-level systems often operate with elevated privileges and present significant attack surfaces. This issue relates to ATT&CK technique T1542.001, which covers 'Taint Data: Modify Boot or Recovery Image', and demonstrates how bootloader vulnerabilities can be leveraged to establish persistent access to target systems. The fix should include runtime checks that validate memory addresses against known safe ranges and implement proper access control mechanisms to prevent unauthorized memory modifications.