CVE-2018-11840 in Android
Summary
by MITRE
In all android releases(Android for MSM, Firefox OS for MSM, QRD Android) from CAF using the linux kernel, while processing the WLAN driver command ioctl a temporary buffer used to construct the reply message may be freed twice.
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Analysis
by VulDB Data Team • 05/17/2023
This vulnerability exists within the linux kernel implementation used in various android platforms including MSM based devices, firefox os for msm, and qrd android releases. The flaw manifests during the processing of wireless local area network driver command ioctl operations where the kernel handles communication between user space applications and the wireless driver subsystem. The issue stems from improper memory management practices within the kernel's wireless driver handling code, specifically involving the allocation and deallocation of temporary buffers used for constructing reply messages to ioctl commands.
The technical root cause of CVE-2018-11840 involves a double free condition occurring in the wireless driver's ioctl processing routine. When the kernel receives a command through the ioctl interface, it allocates a temporary buffer to construct the response message. However, due to flawed logic in the code path, this temporary buffer gets freed twice during the processing sequence. The first free operation occurs when the buffer is properly handled, but a subsequent code path attempts to free the same memory location again, leading to undefined behavior and potential memory corruption.
This vulnerability falls under the category of memory safety issues and can be classified as CWE-415 Double Free according to the Common Weakness Enumeration standards. The operational impact of this vulnerability extends beyond simple memory corruption, as it creates opportunities for privilege escalation and system instability. An attacker who can control the parameters of the ioctl command could potentially trigger the double free condition and leverage it to execute arbitrary code with kernel privileges, effectively compromising the entire system. The vulnerability affects multiple android variants and is particularly concerning because it resides in the core kernel networking subsystem that handles wireless communications.
The exploitation of this vulnerability requires careful crafting of ioctl parameters to trigger the specific code path leading to the double free condition. Attackers may utilize this flaw to gain kernel-level privileges, which would allow them to bypass normal security restrictions and access sensitive system resources. The impact is particularly severe in mobile environments where wireless connectivity is fundamental to device operation, making this vulnerability a critical threat to device security and user privacy. Organizations should implement immediate mitigations including kernel updates from device manufacturers, disabling unnecessary wireless functionality, and monitoring for anomalous system behavior that might indicate exploitation attempts.
From an attack framework perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1068 privilege escalation tactics. The double free condition creates a memory corruption vulnerability that can be leveraged to execute malicious code at kernel level, which represents a significant escalation from typical user-space attacks. Security professionals should consider this vulnerability as part of broader memory safety assessments and ensure comprehensive patch management processes are in place to address similar issues in kernel subsystems. The vulnerability demonstrates the critical importance of proper memory management in kernel code and highlights the need for thorough code review processes to identify potential double free conditions and other memory safety issues.