CVE-2017-11030 in Android
Summary
by MITRE
In Android for MSM, Firefox OS for MSM, QRD Android, with all Android releases from CAF using the Linux kernel, in the HDMI video driver function hdmi_edid_sysfs_rda_res_info(), userspace can perform an arbitrary write into kernel memory.
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Analysis
by VulDB Data Team • 12/21/2019
This vulnerability exists within the HDMI video driver component of Android-based systems that utilize the Linux kernel from the Code Aurora Forum. The flaw resides in the hdmi_edid_sysfs_rda_res_info() function where improper input validation allows userspace processes to manipulate kernel memory directly through sysfs interfaces. This represents a critical privilege escalation vector that violates fundamental kernel security principles by enabling unprivileged userspace code to write arbitrary data to kernel memory locations. The vulnerability stems from insufficient bounds checking and validation mechanisms within the driver's sysfs attribute handling, creating a path where malicious userspace applications can craft specially formatted input to overwrite kernel memory regions. Such arbitrary kernel memory writes can lead to complete system compromise through privilege escalation, memory corruption, or potential code execution within kernel space. The impact extends across multiple Android variants including MSM-based devices, Firefox OS for MSM, and QRD Android platforms, affecting all releases from CAF that utilize the Linux kernel. This vulnerability directly maps to CWE-787: Out-of-bounds Write, which is categorized under the broader class of buffer overflow vulnerabilities. The ATT&CK framework would classify this under T1068: Exploitation for Privilege Escalation, specifically targeting kernel-level privilege escalation techniques. The security implications are severe as attackers can leverage this to gain root access to the device, potentially leading to full system compromise and data exfiltration. The vulnerability is particularly concerning in mobile environments where kernel exploits can result in persistent backdoors and complete device takeover.
The technical implementation of this flaw involves the HDMI driver's handling of sysfs attributes related to EDID (Extended Display Identification Data) information. When userspace applications interact with the hdmi_edid_sysfs_rda_res_info() function through sysfs interfaces, they can provide input that bypasses proper validation checks. This allows them to specify arbitrary memory addresses within kernel space and write data to those locations. The lack of proper bounds checking means that input parameters are not validated against legitimate memory ranges, enabling attackers to overwrite critical kernel structures, function pointers, or other sensitive memory locations. This type of vulnerability is classified as a kernel-level buffer overflow or memory corruption issue, where the attacker can control both the target memory location and the data being written. The vulnerability is particularly dangerous because it operates at the kernel level where all system security mechanisms are bypassed, allowing for complete system compromise without requiring additional exploitation primitives. The attack surface is broad as it affects all devices running affected Android variants, making it a widespread security concern across multiple device manufacturers and platforms.
Mitigation strategies for this vulnerability require immediate patching of affected kernel versions through security updates from device manufacturers and the Code Aurora Forum. System administrators should prioritize applying kernel updates that address the specific buffer overflow in the HDMI driver's sysfs handling. Device manufacturers need to implement proper input validation and bounds checking within the hdmi_edid_sysfs_rda_res_info() function to prevent userspace from providing malicious input that could lead to kernel memory corruption. Additional defensive measures include implementing kernel memory protection mechanisms such as kernel address space layout randomization and stack canaries to make exploitation more difficult. The security community should also consider implementing runtime monitoring to detect suspicious sysfs attribute access patterns that could indicate exploitation attempts. Organizations should conduct thorough vulnerability assessments to identify all affected devices and ensure timely deployment of patches. Network-level monitoring can help detect potential exploitation attempts by monitoring for unusual sysfs access patterns. Given the severity of this vulnerability, immediate action is required to protect against potential exploitation by threat actors who may be actively targeting these kernel-level weaknesses in mobile devices. The vulnerability's classification under CWE-787 indicates that it should be addressed through proper bounds checking and input validation practices that are standard in secure software development lifecycle processes.