CVE-2018-5823 in Android
Summary
by MITRE
In Qualcomm Android for MSM, Firefox OS for MSM, and QRD Android with all Android releases from CAF using the Linux kernel before security patch level 2018-04-05, improper buffer length validation in extscan hotlist event can lead to potential buffer overflow.
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Analysis
by VulDB Data Team • 05/31/2020
The vulnerability identified as CVE-2018-5823 represents a critical buffer overflow issue affecting Qualcomm Android, Firefox OS for MSM, and QRD Android platforms running Linux kernel versions prior to the 2018-04-05 security patch level. This flaw resides within the extscan hotlist event handling mechanism, which is part of the wireless networking subsystem responsible for managing extended scan operations in mobile devices. The vulnerability stems from inadequate validation of buffer lengths during the processing of hotlist events, creating an exploitable condition that could allow malicious actors to manipulate memory structures through carefully crafted input data. The affected platforms include various Qualcomm MSM (Mobile Services Module) implementations that utilize the Linux kernel as their underlying operating system foundation, making this vulnerability widespread across numerous mobile devices manufactured by different OEMs.
The technical implementation of this vulnerability involves the improper handling of buffer length parameters during extscan hotlist event processing within the wireless networking driver components. When the system processes hotlist events related to extended scanning operations, it fails to properly validate the length of input buffers before copying data into fixed-size memory regions. This omission creates a classic buffer overflow condition where an attacker can provide input data exceeding the allocated buffer space, potentially overwriting adjacent memory locations including return addresses, function pointers, or other critical program state information. The vulnerability specifically impacts the Linux kernel's wireless subsystem implementation on Qualcomm platforms, where the extscan functionality is used to manage networks of interest for automatic scanning and connection purposes. The flaw demonstrates characteristics consistent with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios, making it a multi-faceted memory corruption vulnerability.
The operational impact of CVE-2018-5823 extends beyond simple denial of service conditions to potentially enable remote code execution capabilities. An attacker who can influence the extscan hotlist event processing could leverage this vulnerability to execute arbitrary code within the kernel context, potentially gaining full system control over affected devices. The attack surface is particularly concerning given that the vulnerability affects multiple mobile platforms including Android, Firefox OS, and QRD Android implementations, suggesting it impacts a substantial portion of the mobile device ecosystem. The vulnerability's exploitation requires minimal privileges since it operates within the kernel space of the wireless subsystem, making it particularly dangerous for mobile devices where users typically do not have direct kernel access. The timing of the vulnerability's discovery and the specific patch level requirement (2018-04-05) indicates that this was a previously unknown flaw that had been present in the codebase for an extended period, allowing potential attackers to develop and deploy exploits before the patch was released.
Mitigation strategies for CVE-2018-5823 primarily focus on applying the vendor-provided security patches released on or after April 5, 2018, which address the buffer length validation issues in the extscan hotlist event handling code. Organizations and device manufacturers should prioritize immediate deployment of these patches across all affected platforms to prevent exploitation attempts. Additionally, network administrators should implement monitoring solutions to detect unusual wireless scanning patterns that might indicate exploitation attempts, as the vulnerability operates within the standard wireless networking functionality that users expect to function normally. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation, particularly in enterprise environments where mobile devices connect to sensitive corporate networks. The vulnerability's classification under the ATT&CK framework would place it within the T1059.007 technique category for kernel-level code execution, making it a critical target for defensive security measures and incident response planning. Device manufacturers should also consider implementing additional input validation checks and memory protection mechanisms to prevent similar vulnerabilities from occurring in future implementations.