CVE-2019-12942 in TTLock
Summary
by MITRE
TTLock devices do not properly block guest access in certain situations where the network connection to the cloud is unavailable.
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Analysis
by VulDB Data Team • 12/19/2023
The CVE-2019-12942 vulnerability affects TTLock smart lock devices that fail to properly enforce guest access restrictions when network connectivity to the cloud service is disrupted. This represents a critical security flaw in IoT device access control mechanisms where the device's local authentication and authorization logic becomes compromised during network outages. The vulnerability stems from the device's inability to maintain consistent security policies when operating in offline mode, creating a scenario where unauthorized access could potentially occur through guest accounts that should be restricted during cloud unavailability. The flaw specifically manifests when the lock device cannot communicate with its cloud infrastructure, causing it to potentially grant access to guests who should be denied access based on established security policies.
This vulnerability directly relates to CWE-305 authentication flaw and CWE-308 use of weak cryptography, as it demonstrates how IoT devices can fail to maintain proper authentication contexts when network connectivity is lost. The technical implementation issue involves the device's state management during network transitions, where it fails to properly validate guest access permissions when operating in a disconnected state. The lock mechanism appears to fall back to a less secure operational mode when cloud communication is unavailable, potentially allowing guest users to bypass normal access controls that would typically be enforced through cloud-based authorization checks. This behavior violates fundamental security principles of defense in depth and secure by default configurations that should apply regardless of network connectivity status.
The operational impact of this vulnerability extends beyond simple access control breaches, as it creates potential for unauthorized physical access to premises protected by TTLock devices. During network outages or cloud service disruptions, malicious actors could exploit this flaw to gain entry through guest accounts that are typically restricted to specific time windows or access parameters. The vulnerability particularly affects environments where guest access is commonly used, such as hotels, rental properties, or shared workspaces where temporary access is required. Security administrators face the challenge of maintaining consistent access control policies across both online and offline operational states, as the device fails to maintain proper security boundaries when network connectivity is lost.
Mitigation strategies for CVE-2019-12942 should focus on implementing robust local access control enforcement that does not depend on network connectivity to cloud services. Device manufacturers should ensure that critical access control decisions are made locally with sufficient cryptographic integrity to prevent unauthorized access even when cloud communication is unavailable. Network segmentation and monitoring solutions can help detect when devices lose connectivity and alert administrators to potential security incidents. Organizations should implement regular security assessments of IoT device configurations and maintain updated firmware to address known vulnerabilities. The ATT&CK framework's TA0001 Initial Access and TA0003 Persistence tactics are relevant here, as this vulnerability could enable attackers to establish persistent access through compromised guest account permissions during network outages. Additionally, implementing zero trust network access principles and maintaining detailed audit logs of access attempts can help detect and respond to exploitation attempts that leverage this vulnerability.