CVE-2015-9002 in Android
Summary
by MITRE
In TrustZone an out-of-range pointer offset vulnerability can potentially occur in a DRM routine in all Android releases from CAF using the Linux kernel.
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Analysis
by VulDB Data Team • 12/24/2020
The vulnerability identified as CVE-2015-9002 represents a critical out-of-range pointer offset issue within the TrustZone security subsystem of Android devices that utilize the Linux kernel. This flaw specifically affects DRM (Digital Rights Management) routines implemented by the Code Aurora Forum (CAF) and impacts all Android versions that incorporate this kernel implementation. The vulnerability exists at the intersection of hardware security and software execution, where TrustZone's secure execution environment fails to properly validate pointer offsets during DRM processing operations. This issue demonstrates a fundamental breakdown in input validation mechanisms within the secure world of the TrustZone architecture.
The technical implementation of this vulnerability stems from inadequate bounds checking within the DRM handling code path that operates within the TrustZone secure monitor. When processing digital rights management operations, the system fails to properly validate the pointer offset values used to access memory regions containing DRM content or metadata. This allows for potential memory corruption scenarios where an attacker could manipulate pointer values to access unauthorized memory locations or cause unintended code execution. The vulnerability manifests as a classic buffer overflow condition that can be exploited to gain elevated privileges within the secure execution environment, bypassing traditional security boundaries between the normal world and secure world of TrustZone.
The operational impact of CVE-2015-9002 extends beyond simple memory corruption, as it represents a pathway for privilege escalation attacks that could compromise the integrity of the entire device security framework. Devices running affected Android versions become vulnerable to attacks that could potentially extract protected content, modify DRM policies, or even gain access to cryptographic keys stored within the secure element. The vulnerability affects a substantial number of Android devices that rely on CAF's kernel implementations, making it particularly dangerous as it impacts multiple device manufacturers and models. This flaw directly violates the fundamental security principles of TrustZone architecture, which is designed to provide isolation between secure and non-secure execution environments.
Mitigation strategies for CVE-2015-9002 require both immediate patching of affected kernel implementations and comprehensive security hardening measures. Device manufacturers must update their kernel implementations to include proper bounds checking and pointer validation mechanisms within the DRM processing routines. The fix should implement proper input validation that verifies all pointer offsets against legitimate memory boundaries before any access occurs. Additionally, system administrators should consider implementing runtime protections such as stack canaries and address space layout randomization to make exploitation more difficult. This vulnerability aligns with CWE-129 and CWE-787 categories related to improper input validation and out-of-bounds writes, and represents a significant concern under ATT&CK framework's privilege escalation techniques that target system-level security components. Organizations should also conduct thorough security assessments of their TrustZone implementations to identify similar vulnerabilities in related security subsystems.
The broader implications of this vulnerability highlight the critical importance of secure coding practices within hardware security modules and the need for comprehensive security testing of trusted execution environments. This flaw demonstrates how seemingly minor input validation issues can result in catastrophic security failures that undermine the entire security architecture of mobile devices. The vulnerability serves as a reminder that security boundaries, particularly those implemented in hardware security modules, require rigorous testing and validation to prevent exploitation through memory corruption attacks that target the fundamental execution environments of secure processors.