CVE-2015-9022 in Android
Summary
by MITRE
In all Android releases from CAF using the Linux kernel, time-of-check Time-of-use (TOCTOU) Race Conditions exist in several TZ APIs.
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Analysis
by VulDB Data Team • 12/27/2020
The vulnerability identified as CVE-2015-9022 represents a critical time-of-check time-of-use race condition flaw affecting Android devices that utilize the Linux kernel from the Code Aurora Forum. This vulnerability specifically impacts the TrustZone (TZ) APIs, which are fundamental components responsible for providing secure execution environments within mobile devices. The race condition occurs when the system performs a security check on a resource and then subsequently uses that same resource without revalidating the security state, creating a window where malicious actors can exploit the temporal gap between verification and utilization.
TOCTOU race conditions are classified under CWE-367, which specifically addresses the dangerous practice of performing security checks and then using resources without proper revalidation. The vulnerability exists in the kernel-level implementations of TrustZone APIs that handle secure communication between the normal world and the secure world of Android devices. This flaw enables attackers to manipulate system resources during the brief interval between when access permissions are verified and when those resources are actually accessed, potentially allowing privilege escalation and unauthorized system access.
The operational impact of this vulnerability is severe as it affects the fundamental security architecture of Android devices, particularly those running kernel versions from the Code Aurora Forum. Attackers can exploit this race condition to bypass security mechanisms designed to protect sensitive system resources, potentially gaining access to secure storage areas, cryptographic keys, or other protected system components. The vulnerability undermines the core principle of secure execution environments by allowing malicious processes to interfere with legitimate secure operations during the temporal window of the race condition, effectively compromising the integrity and confidentiality of data protected by TrustZone APIs.
Mitigation strategies for CVE-2015-9022 require immediate patching of affected kernel versions through updates from device manufacturers and the Code Aurora Forum. System administrators should implement comprehensive monitoring for suspicious access patterns and resource manipulation during system calls that interact with TrustZone APIs. The vulnerability aligns with ATT&CK technique T1068, which involves exploiting local privilege escalation opportunities, and T1547, which addresses privilege escalation through kernel-level vulnerabilities. Device manufacturers must ensure proper synchronization mechanisms are implemented in kernel-level APIs to prevent the temporal gap that enables this race condition, requiring careful review of all system call implementations that interact with secure execution environments. Additionally, the vulnerability demonstrates the importance of following secure coding practices that prevent temporal race conditions in critical system components, particularly those handling security-sensitive operations within trusted execution environments.