CVE-2017-11040 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, when reading from sysfs nodes, one can read more information than it is allowed to.
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Analysis
by VulDB Data Team • 01/13/2021
The vulnerability identified as CVE-2017-11040 represents a critical information disclosure flaw within Qualcomm's Android implementations that leverages improper access control mechanisms in the Linux kernel subsystem. This issue affects all Qualcomm products utilizing Android releases from the Code Aurora Forum (CAF) environment, creating a persistent security weakness that undermines the integrity of the system's information protection measures. The flaw manifests specifically within the sysfs node access controls, where the kernel fails to properly enforce read permissions for sensitive system information that should be restricted to authorized processes only.
The technical root cause of this vulnerability stems from inadequate validation of access permissions when processing read operations against sysfs nodes within the Linux kernel implementation. Sysfs is a virtual filesystem that exposes kernel data structures to userspace applications, typically used for system configuration and monitoring purposes. In this case, the kernel's permission checking mechanism fails to properly validate whether requesting processes possess adequate privileges to access specific sysfs nodes, allowing unauthorized entities to read kernel memory contents, device information, or other sensitive data that should remain protected. This represents a classic example of improper access control as categorized under CWE-284, where the system fails to properly enforce access restrictions on system resources.
The operational impact of CVE-2017-11040 extends beyond simple information disclosure, as it provides attackers with potential pathways to gather sensitive system information that could be leveraged for further exploitation. An attacker with local access to a vulnerable device could potentially extract kernel memory addresses, device driver information, or other confidential data that could aid in crafting more sophisticated attacks. This vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1007 (System Service Discovery) by enabling unauthorized access to system information that would normally be restricted. The flaw particularly affects devices running Android versions that utilize Qualcomm's kernel modifications, making it prevalent across numerous smartphones, tablets, and other mobile devices that rely on Qualcomm's hardware platforms.
Mitigation strategies for this vulnerability require immediate implementation of kernel-level patches that properly enforce access controls on sysfs node read operations. System administrators and device manufacturers should prioritize updating to patched kernel versions that address the improper permission validation logic. Additionally, implementing runtime monitoring of sysfs access patterns can help detect anomalous behavior that might indicate exploitation attempts. The solution should also include proper privilege escalation controls and comprehensive access logging to maintain audit trails of sysfs node interactions. Organizations should consider applying the principle of least privilege to all sysfs access operations and regularly review access control policies to prevent similar vulnerabilities from emerging in other kernel subsystems. This remediation approach addresses both the immediate security concern and helps establish stronger foundation for preventing future access control violations within the Linux kernel environment.