CVE-2020-21406 in Smart TV Box MAX
Summary
by MITRE • 07/20/2022
An issue was discovered in RK Smart TV Box MAX and V88 SmartTV box that allows attackers to cause a denial of service via the switchNextDisplayInterface service.
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Analysis
by VulDB Data Team • 08/15/2022
The vulnerability identified as CVE-2020-21406 affects RK Smart TV Box MAX and V88 SmartTV box devices, representing a critical denial of service weakness within embedded smart television systems. This flaw manifests through the switchNextDisplayInterface service, which is designed to manage display interface switching operations within the device's operating environment. The vulnerability stems from insufficient input validation and improper handling of service calls within the device's middleware architecture, creating an exploitable condition that can be leveraged by remote attackers to disrupt normal device operations.
The technical implementation of this vulnerability involves a lack of proper bounds checking and parameter validation within the switchNextDisplayInterface service routine. When an attacker sends malformed or specially crafted requests to this service, the system fails to properly validate the incoming parameters, leading to potential buffer overflows or memory corruption conditions. This type of flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The vulnerability exists at the service level within the device's communication stack, making it accessible through network-based attack vectors without requiring physical access to the device.
From an operational impact perspective, this vulnerability creates significant security implications for users and organizations deploying these smart TV devices in both residential and commercial environments. The denial of service condition can render the affected devices completely non-functional, preventing legitimate users from accessing television services, streaming content, or utilizing other device features. In commercial settings such as hotels, retail establishments, or corporate environments, this vulnerability could result in substantial operational disruption and potential financial losses. The attack surface is particularly concerning given that these devices are often deployed in public or semi-public locations where network accessibility is guaranteed, making them prime targets for exploitation.
The attack pattern associated with CVE-2020-21406 follows the tactics described in the MITRE ATT&CK framework under the T1499 category, specifically targeting network denial of service conditions. Attackers can exploit this vulnerability through remote network access, potentially leveraging automated scanning tools to identify affected devices within their target network segments. The exploitation process typically involves sending specially crafted service requests that trigger the buffer overflow condition, causing the device to crash or become unresponsive. This vulnerability demonstrates the importance of proper input validation and secure coding practices within embedded systems, particularly those handling user interface operations and display management functions.
Mitigation strategies for this vulnerability should include immediate firmware updates from manufacturers, network segmentation to limit access to affected devices, and implementation of intrusion detection systems to monitor for suspicious service requests. Organizations should also consider disabling unnecessary network services and implementing proper access controls to prevent unauthorized exploitation. The vulnerability highlights the critical need for robust security testing and code review processes within embedded device development, particularly focusing on service interfaces that handle user input or system configuration changes. Regular security assessments and vulnerability scanning of deployed smart TV devices are essential to identify and remediate similar weaknesses that could compromise device availability and user experience.