CVE-2020-0004 in Android
Summary
by MITRE
In generateCrop of WallpaperManagerService.java, there is a possible sysui crash due to image exceeding maximum texture size. This could lead to local denial of service with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android-8.0, Android-8.1, Android-9, and Android-10 Android ID: A-120847476
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Analysis
by VulDB Data Team • 03/20/2024
The vulnerability identified as CVE-2020-0004 resides within the WallpaperManagerService.java component of Android operating systems spanning versions 8.0, 8.1, 9, and 10. This issue manifests in the generateCrop method where improper handling of image dimensions can lead to system instability. The flaw specifically targets the graphics rendering pipeline where wallpaper images are processed and cropped to fit display requirements. When an image exceeds the maximum texture size supported by the graphics hardware, the system encounters a critical failure during the wallpaper generation process. This condition triggers a crash in the SystemUI component which is responsible for managing the user interface elements including the wallpaper functionality. The vulnerability represents a classic buffer overflow scenario where memory allocation exceeds hardware limitations, leading to an unhandled exception that terminates the system service. According to CWE-129, this vulnerability falls under improper validation of array indices, specifically manifesting as an insufficient check for maximum texture size limits. The attack surface is particularly concerning as it operates entirely within the system's core services without requiring any user interaction or elevated privileges to exploit.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable persistent denial of service conditions. When the WallpaperManagerService crashes, users lose the ability to change or view wallpapers until the system reboots or the service restarts automatically. This crash can occur during normal wallpaper operations, such as setting a new wallpaper or rotating through multiple background images. The instability affects the entire user interface experience since SystemUI components are fundamental to Android's visual presentation layer. From an attacker perspective, this vulnerability represents a low-effort method for causing system instability that requires no specialized tools or user engagement. The exploitability is particularly high because the vulnerability is triggered by legitimate image processing operations rather than malicious input. The absence of user interaction requirements places this vulnerability in the ATT&CK framework under T1499.004 for Network Denial of Service, though the implementation is more accurately classified as a local denial of service through system service corruption.
Mitigation strategies for CVE-2020-0004 should focus on implementing proper input validation and boundary checking within the image processing pipeline. Android security patches addressing this vulnerability typically include enhanced bounds checking for texture size limits and improved error handling during image processing operations. System administrators and device manufacturers should prioritize applying the relevant security updates immediately, as the vulnerability exists in multiple Android versions and provides a straightforward path to system instability. Additional protective measures include implementing runtime monitoring for SystemUI service crashes and establishing automated recovery mechanisms. The vulnerability highlights the importance of proper resource management in graphics-intensive applications and demonstrates how seemingly benign operations can lead to critical system failures. Organizations should also consider implementing network-level monitoring to detect unusual patterns of system service crashes that might indicate exploitation attempts. The fix typically involves adding explicit checks for maximum texture dimensions before image processing begins, preventing the system from attempting to allocate memory that exceeds hardware capabilities. This vulnerability serves as a reminder of the critical importance of validating all system inputs and implementing robust error handling in core operating system services, particularly those handling multimedia content.