CVE-2018-6243 in Android
Summary
by MITRE
NVIDIA Tegra TLK Widevine Trust Application contains a vulnerability in which missing the input parameter checking of video metadata count may lead to Arbitrary Code Execution, Denial of Service or Escalation of Privileges. Android ID: A-72315075. Severity Rating: High. Version: N/A.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2018-6243 resides within the NVIDIA Tegra Trust Application Layer Kernel (TLK) implementation of the Widevine digital rights management system. This flaw specifically affects the handling of video metadata parameters within the trust application environment, creating a critical security gap that impacts devices running Android operating systems with NVIDIA Tegra processors. The vulnerability manifests as a missing input validation mechanism that fails to properly verify the count parameter associated with video metadata structures, representing a fundamental breakdown in the security architecture of the trusted execution environment.
The technical flaw stems from inadequate parameter validation within the TLK component responsible for processing Widevine DRM content on Tegra-based devices. When the system processes video metadata, it fails to validate the expected count of metadata entries, allowing malicious actors to craft specially crafted inputs that can bypass normal parameter checking routines. This missing validation creates a path for exploitation where attacker-controlled data can flow directly into critical system functions without proper sanitization or bounds checking. The vulnerability is categorized under CWE-20 as "Improper Input Validation," which directly relates to the absence of proper parameter verification mechanisms in the codebase.
The operational impact of this vulnerability spans multiple security domains including arbitrary code execution, denial of service, and privilege escalation capabilities. An attacker exploiting this vulnerability could potentially execute malicious code within the trusted execution environment, effectively bypassing the security boundaries that separate normal system operations from privileged kernel activities. The denial of service aspect occurs when malformed metadata inputs cause the system to crash or become unresponsive, while the privilege escalation component allows attackers to gain elevated system privileges that would normally be restricted. This vulnerability directly impacts the integrity and confidentiality of the device's secure processing environment, potentially compromising all content protected by Widevine DRM.
The exploitation of this vulnerability requires careful crafting of video metadata structures that manipulate the expected parameter count, leading to memory corruption or control flow hijacking within the TLK environment. Attackers could leverage this weakness through malicious media content or by manipulating the device's media processing pipeline to trigger the vulnerable code path. The attack surface extends to any device utilizing NVIDIA Tegra processors with Widevine DRM support, making it particularly concerning for mobile devices and embedded systems where the trusted execution environment is critical for security. This vulnerability aligns with ATT&CK technique T1059.007 for execution through kernel modules and T1068 for privilege escalation through kernel exploitation.
Mitigation strategies for CVE-2018-6243 primarily involve applying the latest security patches provided by NVIDIA and device manufacturers, as well as implementing runtime protections such as stack canaries and input validation routines. Organizations should also consider deploying network monitoring solutions to detect suspicious media processing activities that might indicate exploitation attempts. The implementation of proper parameter validation and bounds checking within the TLK component represents the fundamental fix required to address this vulnerability. Device manufacturers should also consider implementing additional security measures such as code integrity checking and secure boot mechanisms to prevent unauthorized modifications to the trusted execution environment components. Regular security audits of trusted application implementations are essential to identify similar validation gaps that could lead to similar exploitation vectors.