CVE-2021-0508 in Android
Summary
by MITRE • 06/21/2021
In various functions of DrmPlugin.cpp, there is a possible use after free due to a race condition. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-8.1 Android-9 Android-10 Android-11Android ID: A-176444154
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Analysis
by VulDB Data Team • 06/24/2021
The vulnerability identified as CVE-2021-0508 resides within the DrmPlugin.cpp component of Android operating systems spanning versions 8.1 through 11. This represents a critical security flaw that stems from improper memory management practices within the digital rights management subsystem. The issue manifests as a use-after-free condition that occurs due to a race condition in multiple functions, creating a pathway for malicious actors to exploit system weaknesses. The vulnerability's classification as a local privilege escalation vector indicates that an attacker with minimal privileges can potentially elevate their access level within the system. This particular flaw does not require user interaction for exploitation, making it particularly concerning as it can be triggered automatically without any direct user involvement or consent. The Android ID A-176444154 further identifies this vulnerability within Google's internal tracking systems, highlighting its significance in the Android security ecosystem.
The technical root cause of this vulnerability lies in the race condition present within the DrmPlugin.cpp functions, where memory deallocation occurs before subsequent memory access operations. This timing issue creates a window where freed memory can be accessed or reused by other processes, leading to unpredictable behavior. When memory is freed and immediately accessed again, the system may either access invalid memory locations or potentially allow code execution in the freed memory space. The race condition aspect indicates that the vulnerability depends on specific timing sequences between concurrent operations, making it challenging to reproduce consistently but not impossible to exploit. The flaw specifically affects the digital rights management functionality within Android, which handles protected media content and DRM-protected applications, making it a prime target for attackers seeking system-level access. This vulnerability directly maps to CWE-416, which describes the use of freed memory condition, and can be categorized under ATT&CK technique T1068, which involves local privilege escalation through system weaknesses.
The operational impact of CVE-2021-0508 extends beyond simple privilege escalation as it provides attackers with enhanced capabilities within the Android environment. Once exploited, the vulnerability allows for unauthorized access to system resources, potentially enabling attackers to modify protected content, access sensitive data, or even install malicious applications with elevated privileges. The local nature of the exploit means that attackers do not need network connectivity or user interaction, making it particularly dangerous in environments where devices may be compromised through other means. The vulnerability affects multiple Android versions, indicating a widespread exposure across the platform's ecosystem, and could potentially allow for persistent access to devices. Attackers could leverage this weakness to gain control over media playback systems, access device encryption keys, or manipulate system configurations. The lack of user interaction requirements makes this vulnerability especially concerning for mobile devices where users may not be actively monitoring for such exploits, and the privilege escalation capability could enable complete system compromise.
Mitigation strategies for CVE-2021-0508 primarily focus on immediate system updates and patches provided by Google and device manufacturers. Organizations and users should prioritize applying the latest Android security updates that address this specific vulnerability, as these patches typically include memory management fixes and race condition protections. System administrators should implement comprehensive monitoring to detect potential exploitation attempts, particularly focusing on unusual memory access patterns or privilege escalation events. Device manufacturers should ensure their security update distribution mechanisms are functioning properly to deliver patches promptly to affected devices. Additional protective measures include implementing application sandboxing, restricting unnecessary system access permissions, and maintaining regular security audits of the device's DRM subsystem. The vulnerability's nature suggests that traditional security measures like firewalls may not prevent exploitation, as the attack vector is internal to the system. Organizations should also consider implementing device integrity checks and runtime monitoring to detect anomalous behavior that might indicate exploitation attempts. Regular security assessments of the Android platform's memory management systems can help identify similar race condition vulnerabilities that may exist in other components of the operating system.