CVE-2019-9455 in Android
Summary
by MITRE
In the Android kernel in the video driver there is a kernel pointer leak due to a WARN_ON statement. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 08/13/2020
The vulnerability identified as CVE-2019-9455 represents a critical kernel pointer leak within the Android kernel's video driver component. This flaw manifests through a WARN_ON statement that inadvertently exposes kernel memory addresses to unauthorized processes, creating a significant information disclosure risk. The vulnerability exists in the kernel's video driver subsystem, which handles graphics processing and display functionality across Android devices. The WARN_ON macro is designed to log warnings when certain conditions are met, but in this case it fails to properly sanitize the memory addresses it outputs, leading to the leakage of kernel pointers.
The technical implementation of this vulnerability stems from improper handling of kernel memory addresses within the video driver's error reporting mechanisms. When the WARN_ON condition is triggered during video processing operations, the kernel's logging mechanism includes raw memory addresses in the warning output without adequate obfuscation or sanitization. This pointer leakage occurs because the kernel driver lacks proper access controls and memory protection mechanisms to prevent unauthorized exposure of kernel-space memory locations. The vulnerability is particularly concerning because it operates at the kernel level where memory addresses can reveal critical information about kernel layout, memory management structures, and potentially even exploit offsets for more sophisticated attacks.
From an operational perspective, this vulnerability enables local information disclosure attacks that require system execution privileges to exploit, meaning that an attacker with local access to the device can potentially extract sensitive kernel memory addresses. The lack of user interaction requirements for exploitation makes this vulnerability particularly dangerous as it can be triggered automatically during normal video processing operations. The leaked kernel pointers can be used by attackers to bypass kernel address space layout randomization defenses, identify kernel function addresses, and potentially construct more advanced exploits. This information leakage creates a foundation for privilege escalation attacks and can significantly reduce the complexity of subsequent exploitation attempts.
The vulnerability aligns with CWE-200, which covers "Information Exposure," and represents a specific instance of improper information handling at the kernel level. From an attack framework perspective, this vulnerability maps to the initial access phase in the MITRE ATT&CK framework where adversaries establish a foothold by gathering intelligence about the target system. The leaked kernel addresses can be leveraged to perform advanced persistent threat operations by providing attackers with the necessary information to craft more effective exploits against the kernel. This vulnerability also demonstrates weaknesses in kernel security architecture and highlights the importance of proper memory management practices in kernel code. Organizations should implement immediate patching strategies and monitor for potential exploitation attempts, while also considering broader kernel security hardening measures to prevent similar information disclosure vulnerabilities from occurring in other subsystems.
The impact of this vulnerability extends beyond simple information disclosure as it provides attackers with critical reconnaissance data that can be used to construct more sophisticated attacks. The kernel pointer leak can reveal memory layout information that is essential for bypassing modern security mitigations such as stack canaries, kernel page table isolation, and other exploit prevention mechanisms. This makes CVE-2019-9455 particularly dangerous in environments where attackers have local access to devices, as it provides them with the foundation for more advanced exploitation techniques. The vulnerability underscores the need for comprehensive kernel security testing and the importance of proper input validation and output sanitization in kernel-space code to prevent similar issues from occurring in other components of the Android kernel.