CVE-2015-9021 in Android
Summary
by MITRE
In all Android releases from CAF using the Linux kernel, access control to SMEM memory was not enabled.
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Analysis
by VulDB Data Team • 12/27/2020
The vulnerability identified as CVE-2015-9021 represents a critical access control flaw within the Android operating system's implementation of the Linux kernel on devices manufactured by Qualcomm Automotive Forum. This issue affects all Android versions that utilize Qualcomm's kernel implementations, creating a fundamental weakness in the system's memory protection mechanisms. The flaw specifically pertains to the Secure Memory (SMEM) subsystem, which is designed to provide protected storage for sensitive data and system configurations. When access controls are disabled or improperly configured, unauthorized processes can gain visibility and manipulation capabilities over memory regions that should remain restricted to privileged system components. This vulnerability directly impacts the integrity and confidentiality of system-level data, as SMEM typically contains critical information such as device identifiers, security keys, and configuration parameters that are essential for maintaining the device's secure operating state.
The technical implementation of this vulnerability stems from the absence of proper access control enforcement within the SMEM memory management subsystem. In standard secure computing environments, memory regions designated for sensitive operations should be protected through strict access control policies that prevent unauthorized read, write, or execute operations. The flaw occurs at the kernel level where the SMEM driver fails to enforce appropriate permission checks, allowing any process running with sufficient privileges to access memory areas that should be restricted to kernel-level operations only. This weakness creates a potential attack surface where malicious applications or compromised processes could exploit the lack of access control to extract sensitive information from SMEM regions, potentially leading to privilege escalation or complete system compromise. The vulnerability manifests as a failure to implement mandatory access controls that should normally be enforced by the kernel's security subsystem.
The operational impact of CVE-2015-9021 extends beyond simple data exposure, as it fundamentally undermines the security model of Android devices that rely on Qualcomm's kernel implementations. Attackers could leverage this vulnerability to extract cryptographic keys, device identification information, or other sensitive data stored in SMEM regions, potentially enabling them to impersonate devices or bypass security mechanisms. The vulnerability is particularly concerning in mobile environments where devices often contain personal data, corporate information, and authentication credentials that are stored in protected memory regions. Additionally, the flaw could facilitate privilege escalation attacks where malicious actors gain elevated system privileges by manipulating memory contents that should remain protected. This vulnerability affects a broad range of devices manufactured by Qualcomm, making it a widespread concern across multiple Android versions and device models that depend on the affected kernel implementations. The impact is further amplified by the fact that SMEM memory regions are often used for storing critical boot parameters and security-related data that are essential for maintaining system integrity.
Mitigation strategies for CVE-2015-9021 should focus on implementing proper access control enforcement within the SMEM subsystem and ensuring that kernel-level memory protection mechanisms are properly configured. System administrators and device manufacturers should prioritize updating to kernel versions that include proper access control implementations for SMEM memory regions, as this vulnerability affects the fundamental security architecture of affected devices. The fix typically involves modifying the kernel driver to enforce strict access controls and permission checks before allowing any process to access SMEM memory areas. Organizations should also consider implementing additional monitoring and detection mechanisms to identify potential exploitation attempts targeting this vulnerability. From a compliance perspective, this vulnerability aligns with CWE-284, which addresses improper access control in software systems, and could be mapped to ATT&CK techniques related to privilege escalation and credential access. Device manufacturers should ensure that their kernel implementations properly enforce mandatory access controls and that security policies are consistently applied across all memory management subsystems to prevent similar vulnerabilities from emerging in future implementations.