CVE-2019-9420 in Android
Summary
by MITRE
In libhevc, there is a possible out of bounds read due to an integer overflow. This could lead to remote denial of service with no additional execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-111272481
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2019-9420 affects the libhevc library component within Android systems, specifically targeting the HEVC (H.265) video decoding functionality. This issue represents a critical security flaw that manifests through an integer overflow condition during video frame processing operations. The vulnerability exists within the video decoding pipeline where the system fails to properly validate integer values during buffer calculations, creating a scenario where arithmetic operations can exceed their intended limits. The affected Android version is Android 10, with the specific Android ID A-111272481 documenting this particular flaw in the system's multimedia processing capabilities.
The technical implementation of this vulnerability stems from improper handling of integer values during HEVC frame parsing and memory allocation processes. When processing maliciously crafted HEVC video streams, the integer overflow condition causes the system to calculate buffer sizes or memory offsets that exceed the valid range for the data type being used. This overflow results in an out-of-bounds memory read operation where the decoder attempts to access memory locations outside the allocated buffer boundaries. The flaw is particularly concerning because it operates at the video decoding layer where untrusted input from external sources can be processed without requiring any elevated privileges or special execution contexts. The vulnerability requires user interaction to be exploited, typically through the playback of malicious video content, making it particularly dangerous in real-world scenarios where users may unknowingly encounter compromised media files.
The operational impact of CVE-2019-9420 extends beyond simple denial of service conditions, potentially allowing attackers to disrupt normal device functionality and create persistent availability issues for users. Remote exploitation capabilities mean that malicious actors can deliver harmful video content through various channels including email attachments, web downloads, or media sharing platforms without requiring users to perform any additional actions beyond viewing the content. This vulnerability aligns with CWE-191, which specifically addresses integer underflow and overflow conditions, and demonstrates how such fundamental mathematical errors can translate into serious security implications within multimedia processing systems. The ATT&CK framework categorizes this vulnerability under T1203, which covers Exploitation for Execution, as the integer overflow can potentially be leveraged to achieve more sophisticated attack vectors beyond simple denial of service. The flaw's location within the libhevc library means that any application or service relying on HEVC video decoding for media playback is potentially exposed to this vulnerability, creating a widespread attack surface across various Android applications and system components that utilize multimedia processing capabilities.
Mitigation strategies for CVE-2019-9420 primarily focus on updating affected Android systems to versions that contain patched implementations of the libhevc library. Organizations and users should prioritize applying the latest security patches from Google and their device manufacturers to address the integer overflow condition. Additionally, implementing network-level filtering to block suspicious video content and disabling automatic media playback for untrusted sources can provide additional protective layers. System administrators should consider monitoring for unusual video processing behavior or memory access patterns that might indicate exploitation attempts. The vulnerability highlights the importance of proper integer validation and bounds checking in multimedia processing libraries, emphasizing the need for rigorous input validation and memory management practices in security-critical components. Regular security audits of multimedia processing libraries should be conducted to identify similar integer overflow conditions that could potentially compromise system integrity and availability.