CVE-2016-3821 in Android
Summary
by MITRE
libmedia in mediaserver in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-08-01 has certain incorrect declarations, which allows remote attackers to execute arbitrary code or cause a denial of service (NULL pointer dereference or memory corruption) via a crafted media file, aka internal bug 28166152.
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Analysis
by VulDB Data Team • 09/09/2022
The vulnerability identified as CVE-2016-3821 affects the libmedia component within the Android mediaserver process, representing a critical security flaw that impacts multiple Android versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before the specified date. This issue stems from incorrect declarations within the media processing framework that create opportunities for remote code execution or denial of service conditions. The vulnerability specifically manifests through NULL pointer dereferences or memory corruption scenarios when processing crafted media files, making it particularly dangerous as it can be exploited through media content delivered over networks or via file transfers.
The technical flaw resides in the improper handling of media file parsing within the mediaserver daemon, where the libmedia library fails to properly validate or sanitize input data from media files. This incorrect declaration pattern creates memory access violations that can be leveraged by attackers to inject malicious code into the system or force the mediaserver process into a crash state. The vulnerability operates at the system level within the Android framework, where media processing occurs in a privileged context, amplifying the potential impact of exploitation. The issue aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a classic example of memory safety vulnerabilities that can lead to arbitrary code execution.
From an operational perspective, this vulnerability presents significant risks to Android devices as it allows remote attackers to compromise systems through media content delivery without requiring user interaction or device-specific privileges. The mediaserver process runs with elevated privileges to handle multimedia operations, making successful exploitation potentially devastating. Attackers could craft malicious media files that, when processed by the vulnerable system, trigger the NULL pointer dereference leading to either complete system compromise or denial of service. The vulnerability's impact extends beyond individual device security to potentially affect entire networks of Android devices, particularly in enterprise environments where media content is frequently shared.
The exploitation of this vulnerability can be achieved through various attack vectors including email attachments, web downloads, or malicious media sharing platforms. The attack surface is broad due to the widespread use of media processing capabilities across Android applications and services. Security researchers have identified that the vulnerability can be triggered through common media formats such as mp4, 3gp, and other container formats that the mediaserver processes. Organizations should consider implementing network-based protections and monitoring for suspicious media file handling activities. The remediation approach requires updating affected Android versions to patched releases, with specific attention to the timeline of 2016-08-01 for Android 6.x versions, as this represents the date when security patches were made available to address the flaw. Additionally, organizations should review their mobile device management policies to ensure timely deployment of security updates and consider network segmentation to limit potential exploitation pathways.
This vulnerability demonstrates the critical importance of memory safety in system-level components and highlights the need for comprehensive security testing of media processing frameworks. The issue represents a convergence of multiple attack techniques including privilege escalation and denial of service, making it particularly challenging to defend against. The ATT&CK framework categorizes this as a privilege escalation and denial of service technique, while the CWE classification emphasizes the memory corruption aspects that make such vulnerabilities particularly dangerous in mobile environments where users frequently interact with multimedia content from untrusted sources.