CVE-2018-5857 in Android
Summary
by MITRE
In the WCD CPE codec, a Use After Free condition can occur in all Android releases(Android for MSM, Firefox OS for MSM, QRD Android) from CAF using the Linux kernel.
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Analysis
by VulDB Data Team • 02/19/2020
The vulnerability identified as CVE-2018-5857 represents a critical use after free condition within the WCD CPE codec implementation across multiple Android variants. This flaw manifests in all Android releases including Android for MSM, Firefox OS for MSM, and QRD Android platforms that utilize the Linux kernel. The WCD CPE codec serves as a crucial component in audio processing pipelines, particularly within Qualcomm-based devices where it handles communication between various audio subsystems and the Linux kernel. The vulnerability stems from improper memory management practices during the codec processing lifecycle, creating opportunities for malicious actors to exploit the freed memory references.
The technical exploitation of this use after free condition occurs when the WCD CPE codec fails to properly invalidate memory pointers after deallocation, allowing subsequent code execution to access already freed memory regions. This memory corruption vulnerability can be triggered through crafted audio input streams or malicious audio processing sequences that manipulate the codec's internal state. The flaw specifically affects the Linux kernel implementation of the Qualcomm Communication Processor Environment CPE codec, which is integral to audio functionality in mobile devices. Attackers can leverage this vulnerability to execute arbitrary code with kernel-level privileges, potentially leading to complete system compromise.
From an operational perspective, this vulnerability poses significant risks to mobile device security as it enables privilege escalation from user-level processes to kernel-level execution. The impact extends across all affected Android variants, making it particularly concerning for device manufacturers and security administrators who must address this issue across their entire product portfolio. The vulnerability's exploitation can result in persistent backdoor access, data exfiltration, and complete device takeover. Given that these Android variants are widely deployed in consumer and enterprise devices, the potential attack surface is extensive. The vulnerability aligns with CWE-416, which specifically addresses use after free conditions, and can be mapped to ATT&CK technique T1068, involving exploitation of legitimate credentials and system privileges.
Mitigation strategies for CVE-2018-5857 require immediate patch deployment across all affected Android platforms, with particular emphasis on updating the Qualcomm CPE codec implementation within the Linux kernel. Device manufacturers should implement memory safety checks and validation routines to prevent improper pointer dereferencing. Security teams must monitor for exploitation attempts and consider implementing runtime protections such as stack canaries and memory protection mechanisms. The vulnerability highlights the importance of rigorous code review processes for kernel-level components and demonstrates the critical need for memory safety practices in embedded audio processing systems. Organizations should also conduct comprehensive vulnerability assessments to identify similar use after free conditions in other kernel modules and audio subsystems, ensuring robust security posture across their mobile device fleets.