CVE-2018-11983 in Android
Summary
by MITRE
In all android releases(Android for MSM, Firefox OS for MSM, QRD Android) from CAF using the linux kernel, Error in kernel observed while accessing freed mask pointers after reallocating memory for mask table.
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Analysis
by VulDB Data Team • 04/22/2020
This vulnerability exists within the linux kernel implementation across multiple android variants including MSM, Firefox OS, and QRD Android platforms. The flaw manifests as a memory management error that occurs during the reallocation process of mask tables, specifically when the kernel attempts to access previously freed memory pointers. This represents a classic use-after-free condition that can lead to arbitrary code execution or system instability. The vulnerability stems from improper handling of memory deallocation and subsequent reallocation processes within the kernel's mask table management subsystem.
The technical implementation involves a race condition or improper pointer management where the kernel reallocates memory for mask tables but fails to properly invalidate or update references to previously freed memory locations. When the system attempts to access these freed pointers, it can result in accessing corrupted or overwritten memory regions. This type of vulnerability falls under the CWE-416 category for use-after-free conditions and can be exploited through kernel-level memory manipulation techniques. The flaw is particularly dangerous because it operates at the kernel level where successful exploitation can grant full system compromise.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable complete system takeover. An attacker with kernel-level access or the ability to trigger the specific memory allocation pattern could leverage this flaw to execute arbitrary code with the highest privileges available to the kernel. This creates a significant threat vector for mobile device security where the adversary could gain root access to the device, extract sensitive data, or install persistent backdoors. The vulnerability affects all versions of android platforms that utilize the linux kernel from code affected by this issue, making it widespread across numerous devices and deployments.
Mitigation strategies should focus on implementing proper memory management practices including immediate pointer invalidation after memory deallocation, proper synchronization mechanisms during reallocation, and comprehensive code reviews of kernel memory management routines. Organizations should prioritize applying vendor patches and updates as soon as available, implementing kernel address space layout randomization where possible, and monitoring for anomalous memory access patterns. The fix typically involves ensuring that all mask table pointers are properly invalidated or updated when memory reallocation occurs, preventing access to freed memory regions. This vulnerability highlights the critical importance of rigorous memory management testing in kernel code and adherence to secure coding practices as outlined in various cybersecurity frameworks and standards.