CVE-2020-0478 in Android
Summary
by MITRE • 12/15/2020
In extend_frame_lowbd of restoration.c, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-150780418
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-0478 resides within the extend_frame_lowbd function in the restoration.c file of Android systems, specifically affecting Android 11 installations. This issue represents a critical security flaw that falls under the category of out-of-bounds write vulnerabilities, which are classified as CWE-787 in the Common Weakness Enumeration catalog. The vulnerability stems from a missing bounds check during frame processing operations, creating a scenario where malicious code could potentially overwrite memory locations beyond the intended buffer boundaries.
The technical flaw manifests when the system processes video frame restoration operations, particularly in low bit-depth frame handling scenarios. During normal operation, the extend_frame_lowbd function should validate input parameters and buffer sizes before performing memory writes. However, the absence of proper bounds checking allows an attacker to manipulate the input data in such a way that memory corruption occurs at arbitrary locations. This type of vulnerability is particularly dangerous because it can be exploited to execute arbitrary code with elevated privileges, as the memory corruption can be leveraged to overwrite critical system structures or function pointers.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables local privilege escalation without requiring additional execution privileges or user interaction for initial exploitation. While the vulnerability description indicates that user interaction is needed for exploitation, the underlying mechanism allows for a sophisticated attack vector that could be chained with other vulnerabilities to achieve system compromise. The Android ID A-150780418 references this specific vulnerability within Google's internal tracking system, highlighting its severity and the need for immediate remediation.
From an attack perspective, this vulnerability aligns with ATT&CK technique T1068, which involves the exploitation of local privilege escalation mechanisms. The attack surface is particularly concerning because it operates within the system's video processing pipeline, which typically runs with elevated privileges to handle multimedia operations. An attacker could potentially craft malicious video content or manipulate existing media files to trigger the vulnerability during normal playback operations, effectively allowing them to execute code with system-level privileges.
Mitigation strategies should focus on implementing proper bounds checking mechanisms within the extend_frame_lowbd function and similar frame processing routines. The fix requires adding comprehensive input validation that verifies buffer sizes and prevents memory writes beyond allocated boundaries. Security patches should also include runtime protections such as address space layout randomization and stack canaries to make exploitation more difficult. Additionally, Android's security model should enforce stricter memory access controls during multimedia processing operations, ensuring that frame restoration functions operate within defined memory boundaries. The vulnerability underscores the importance of rigorous code review processes and automated static analysis tools to identify similar issues in complex multimedia processing pipelines.