CVE-2017-6296 in Android
Summary
by MITRE
"NVIDIA TrustZone Software contains a TOCTOU issue in the DRM application which may lead to the denial of service or possible escalation of privileges. This issue is rated as moderate."
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Analysis
by VulDB Data Team • 01/10/2020
The vulnerability identified as CVE-2017-6296 resides within NVIDIA TrustZone software, specifically affecting the DRM application component. This represents a classic time-of-check to time-of-use vulnerability that exploits a temporal gap between when a security check is performed and when the system actually uses the checked resource. The TOCTOU flaw manifests in the TrustZone environment where the system performs validation checks on digital rights management operations but fails to maintain consistent state validation throughout the execution process. Such vulnerabilities are particularly dangerous in secure enclaves like TrustZone because they can undermine the fundamental security assumptions that these isolated environments are designed to provide.
The technical nature of this vulnerability stems from improper state management within the DRM application's interaction with TrustZone services. When the system performs access validation on a resource, it may validate that access is permitted at the time of the check, but between that validation and the actual resource usage, the system state can change. This creates an exploitable window where an attacker could manipulate the system state to bypass security checks that were previously deemed valid. The vulnerability specifically affects the TrustZone software implementation and its integration with DRM functionality, making it particularly concerning for devices that rely on NVIDIA's secure processing capabilities.
From an operational impact perspective, this vulnerability could enable attackers to achieve either denial of service conditions or privilege escalation within the TrustZone environment. The moderate rating suggests that while the vulnerability does not provide complete system compromise, it represents a significant security risk that could be leveraged by adversaries to disrupt normal operations or gain elevated privileges within the secure processing context. The TrustZone environment is designed to provide hardware-level security isolation, and vulnerabilities that can bypass or manipulate this isolation represent a serious threat to device security and user privacy. This type of vulnerability particularly impacts mobile devices, embedded systems, and other platforms where NVIDIA's secure processing capabilities are integrated for protecting sensitive data and content.
Mitigation strategies for CVE-2017-6296 should focus on implementing proper state validation mechanisms within the DRM application and ensuring that all security checks remain valid throughout the entire execution process. Organizations should prioritize applying NVIDIA security patches and updates as soon as they become available, as these typically address the specific TOCTOU race conditions that enable this vulnerability. The fix likely involves modifying the TrustZone software to maintain consistent state validation across the entire resource access lifecycle, ensuring that checks performed at the time of validation remain relevant when the actual resource usage occurs. This vulnerability aligns with CWE-367 which specifically addresses Time-of-Check to Time-of-Use flaws, and could potentially map to ATT&CK technique T1068 which covers local privilege escalation through system vulnerabilities. Device manufacturers and users should also consider implementing additional monitoring for anomalous access patterns that might indicate exploitation attempts, particularly within secure processing environments where such vulnerabilities can have significant impact on overall system security posture.