CVE-2015-8999 in Android
Summary
by MITRE
In TrustZone a buffer overflow vulnerability can potentially occur in all Android releases from CAF using the Linux kernel while loading an ELF file.
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Analysis
by VulDB Data Team • 12/24/2020
The vulnerability identified as CVE-2015-8999 represents a critical buffer overflow condition within the TrustZone security framework of Android devices. This flaw exists in the Linux kernel implementation used by Qualcomm Android devices and specifically manifests during the process of loading ELF (Executable and Linkable Format) files. The vulnerability stems from inadequate bounds checking mechanisms within the kernel's handling of executable file structures, creating a potential entry point for malicious actors to exploit the system's security boundaries.
This buffer overflow vulnerability operates at the intersection of kernel-level memory management and hardware security features, making it particularly dangerous as it can potentially bypass traditional security measures. The flaw affects all Android releases utilizing Qualcomm's Android framework and is directly related to how the Linux kernel processes executable file formats when they are loaded into memory. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, where insufficient validation allows an attacker to write beyond allocated memory boundaries. The exploitation of this vulnerability could enable unauthorized code execution within the kernel space, potentially compromising the integrity of the entire TrustZone security environment.
The operational impact of CVE-2015-8999 extends beyond simple memory corruption, as it can enable attackers to escalate privileges and gain unauthorized access to sensitive system resources. When an ELF file is loaded, the vulnerable kernel code fails to properly validate input data lengths, allowing malicious payloads to overwrite adjacent memory locations. This creates opportunities for attackers to execute arbitrary code with kernel-level privileges, effectively breaking down the security isolation that TrustZone is designed to maintain. The vulnerability is particularly concerning because it operates at a fundamental level of the system architecture, potentially allowing attackers to circumvent hardware-based security features and access secure elements that should remain protected from normal user-space processes.
The exploitation of this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the Tactic of Privilege Escalation and Defense Evasion. Attackers could leverage this flaw to gain root access to devices, potentially enabling them to install persistent backdoors or extract sensitive cryptographic keys stored within the TrustZone environment. The vulnerability affects devices running Android versions from the earliest releases that utilize Qualcomm's kernel implementation, making it a widespread concern across numerous device models and manufacturers. Security researchers have noted that the attack surface is particularly broad due to the fundamental nature of ELF file loading operations, which occur frequently during normal device operation. Organizations should implement immediate mitigations including kernel updates, input validation patches, and runtime monitoring to detect potential exploitation attempts. The vulnerability also highlights the importance of secure coding practices in kernel development, particularly around memory management and input validation, as specified in industry standards for secure software development lifecycle processes.