CVE-2017-9689 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, a specially-crafted HDMI CEC message can be used to cause stack memory corruption.
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Analysis
by VulDB Data Team • 12/22/2019
This vulnerability exists within the Linux kernel implementation used across various Android variants including MSM platforms, Firefox OS for MSM, and QRD Android systems. The flaw specifically affects devices that utilize the Linux kernel from Code Aurora Forum (CAF) and represents a critical memory corruption issue that can be exploited through HDMI Consumer Electronics Control (CEC) protocols. The vulnerability stems from insufficient input validation and memory management within the kernel's HDMI CEC handling subsystem, where maliciously crafted CEC messages can trigger buffer overflows or other memory corruption conditions.
The technical implementation of this vulnerability allows an attacker to send specially crafted HDMI CEC messages that bypass normal protocol validation checks. When the kernel processes these malformed messages, it fails to properly bounds-check the incoming data before copying it into fixed-size kernel buffers. This results in stack memory corruption that can potentially lead to arbitrary code execution or system crashes. The vulnerability is particularly concerning because HDMI CEC is typically enabled by default on most devices and operates at a low level within the kernel space, making exploitation relatively straightforward from external sources.
From an operational impact perspective, this vulnerability affects a broad range of devices including smartphones, tablets, and embedded systems that utilize the affected kernel versions. The exploitation vector requires only the ability to send HDMI CEC messages, which can be achieved through various means including physical access to HDMI ports, malicious HDMI devices, or network-based attacks if HDMI CEC is exposed through other interfaces. The potential consequences include complete system compromise, data theft, persistent backdoor installation, and denial of service conditions that can render devices inoperable. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow and represents a significant risk to device security and user privacy.
Mitigation strategies should focus on immediate kernel updates and patches provided by device manufacturers, as well as network-level restrictions on HDMI CEC communications when possible. System administrators should disable HDMI CEC functionality when not required, implement proper input validation at kernel boundaries, and monitor for suspicious HDMI traffic patterns. The ATT&CK framework categorizes this vulnerability under T1068 Exploitation for Privilege Escalation and T1059 Command and Scripting Interpreter, as exploitation typically involves leveraging kernel-level privileges to gain persistent access. Organizations should also consider implementing hardware-based security measures and regular security assessments to identify similar vulnerabilities in embedded systems and kernel components.