CVE-2021-1029 in Android
Summary
by MITRE • 12/15/2021
In setClientStateLocked of SurfaceFlinger.cpp, there is a possible out of bounds write due to a use after free. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-193034677
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Analysis
by VulDB Data Team • 12/22/2021
The vulnerability identified as CVE-2021-1029 resides within the SurfaceFlinger component of Android's graphics system, specifically in the setClientStateLocked function of SurfaceFlinger.cpp. This represents a critical security flaw that demonstrates a classic use-after-free condition, where memory previously deallocated is accessed or modified. The vulnerability occurs in the Android 12 operating system and is tracked under Android ID A-193034677, indicating its severity and the need for immediate attention.
The technical implementation of this flaw involves an out-of-bounds write operation that arises from improper memory management within SurfaceFlinger's client state handling mechanism. When the setClientStateLocked function processes client state changes, it fails to properly validate memory references, leading to a scenario where freed memory locations are accessed for writing operations. This use-after-free condition creates a predictable pattern that can be exploited to corrupt memory structures and potentially execute arbitrary code. The vulnerability stems from CWE-416 which specifically addresses use-after-free conditions in software implementations.
The operational impact of this vulnerability extends to local privilege escalation, allowing an attacker with minimal privileges to elevate their access level within the Android system. Since no additional execution privileges are required for exploitation and user interaction is not necessary, the vulnerability presents a particularly dangerous attack surface. An attacker could leverage this flaw to gain system-level privileges, potentially compromising the entire device. This aligns with ATT&CK technique T1068 which covers local privilege escalation through software vulnerabilities, making this a significant concern for Android device security.
The exploitation of this vulnerability demonstrates the critical nature of graphics system components in mobile operating systems, where surface flinger handles the composition and rendering of graphical elements across multiple applications. The flaw represents a fundamental breakdown in memory management within the Android framework, where the system fails to properly manage the lifecycle of client state objects. This allows for memory corruption that can be leveraged to execute malicious code with elevated privileges, potentially leading to complete device compromise.
Mitigation strategies for CVE-2021-1029 primarily focus on applying the relevant Android security patches and updates provided by Google. Organizations and users should immediately implement the security updates released for Android 12 to address this vulnerability. Additionally, system administrators should consider implementing monitoring solutions to detect anomalous memory access patterns that might indicate exploitation attempts. The vulnerability highlights the importance of proper memory management practices and the need for comprehensive code review processes, particularly for critical system components like SurfaceFlinger that handle sensitive graphics operations and maintain system integrity across multiple applications.