CVE-2019-9423 in Android
Summary
by MITRE
In opencv calls that use libpng, 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 required. User interaction is not required for exploitation. Product: AndroidVersions: Android-10Android ID: A-110986616
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2019-9423 represents a critical out-of-bounds write flaw within the OpenCV library when processing images through libpng integration on Android platforms. This issue stems from insufficient input validation mechanisms that fail to properly verify array boundaries during image decompression operations. The flaw exists in the image processing pipeline where OpenCV leverages libpng for handling png format images, creating a scenario where maliciously crafted image files can trigger memory corruption. The vulnerability is classified as a buffer overflow condition that occurs when the application attempts to write data beyond the allocated memory boundaries, potentially allowing attackers to overwrite adjacent memory regions with controlled data.
The technical exploitation of this vulnerability occurs through the improper handling of image metadata within the libpng library integration. When OpenCV processes png files, it relies on libpng to decode image headers and pixel data, but the bounds checking mechanism fails to validate the dimensions specified in the image file against the actual memory allocation. This missing validation allows an attacker to craft a specially formatted png image that contains malformed dimension parameters, causing the decompression routine to write beyond allocated buffer space. The vulnerability specifically affects Android 10 systems where the OpenCV library is integrated into various applications, making it particularly dangerous as it can be exploited through any application that processes png images without proper input sanitization.
The operational impact of CVE-2019-9423 extends beyond simple memory corruption, as it enables local privilege escalation without requiring additional execution privileges or user interaction. This means that any application running with standard user privileges could potentially leverage this vulnerability to elevate its privileges to system level access, effectively bypassing Android's security model. The attack vector is particularly concerning because exploitation requires no user interaction, making it suitable for automated attacks that could be deployed through malicious applications or compromised systems. The vulnerability essentially provides a pathway for attackers to gain root access to Android devices, allowing them to modify system files, install malicious software, or extract sensitive data from the device.
The vulnerability aligns with CWE-129, which specifically addresses "Improper Validation of Array Index" and falls under the broader category of memory safety issues in software development. From an adversary perspective, this flaw maps directly to ATT&CK technique T1068, which involves exploiting local privilege escalation vulnerabilities, and T1059, which covers the execution of malicious code through system-level access. The exploitation process follows a typical attack pattern where an attacker crafts a malicious png file containing oversized dimension values, then places this file within an application that processes images through OpenCV, triggering the out-of-bounds write condition that ultimately results in privilege escalation. This vulnerability demonstrates the critical importance of input validation in security-sensitive libraries and highlights how seemingly minor flaws in image processing components can have severe system-wide consequences.
Mitigation strategies for CVE-2019-9423 primarily focus on updating the affected OpenCV library components to versions that include proper bounds checking mechanisms for libpng integration. Android device manufacturers should prioritize rolling out security patches that address this vulnerability through system updates, particularly targeting devices running Android 10. Organizations should also implement application sandboxing measures that limit the ability of applications to process untrusted image files, and consider deploying runtime monitoring solutions that can detect anomalous memory access patterns. Additionally, developers should conduct thorough code reviews of image processing components to ensure proper bounds validation is implemented, and should avoid using vulnerable library versions in their applications. The recommended approach includes both immediate patch deployment and long-term architectural improvements to prevent similar vulnerabilities from occurring in future implementations of image processing libraries.