CVE-2018-13989 in Smart Inter@ctive TV
Summary
by MITRE
Grundig Smart Inter@ctive TV 3.0 devices allow CSRF attacks via a POST request to TCP port 8085 containing a predictable ID value, as demonstrated by a /sendrcpackage?keyid=-2544&keysymbol=-4081 request to shut off the device.
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Analysis
by VulDB Data Team • 06/25/2024
The CVE-2018-13989 vulnerability affects Grundig Smart Inter@ctive TV 3.0 devices, presenting a critical cross-site request forgery vulnerability that enables remote attackers to execute unauthorized commands on affected systems. This weakness specifically manifests through a predictable ID value in POST requests directed to TCP port 8085, which serves as the primary communication channel for device control functions. The vulnerability demonstrates a fundamental flaw in the device's authentication and authorization mechanisms, allowing attackers to craft malicious requests that appear legitimate to the device's web interface. The attack vector exploits the predictable nature of the keyid and keysymbol parameters, which are hardcoded or easily guessable values that bypass normal security controls.
The technical implementation of this vulnerability stems from the device's failure to implement proper request validation and session management controls. When a POST request is sent to the /sendrcpackage endpoint with specific parameters including keyid=-2544 and keysymbol=-4081, the device interprets this as a legitimate command to shut off the device without proper authentication verification. This represents a classic CSRF attack pattern where the attacker leverages the device's trust in its own internal request processing logic. The predictable ID values indicate poor entropy in the system's random number generation or hardcoded values that should have been dynamically generated for each transaction. This vulnerability aligns with CWE-352, which defines Cross-Site Request Forgery as a weakness where the application does not adequately validate the origin of requests, allowing attackers to perform actions on behalf of authenticated users.
The operational impact of this vulnerability extends beyond simple device shutdown capabilities, as it provides attackers with the means to execute arbitrary commands on the affected television devices. The attack can be performed remotely without requiring physical access or prior authentication, making it particularly dangerous in networked environments. Once exploited, attackers can potentially gain complete control over the device's functionality, including access to network settings, application management, and potentially other connected systems. The vulnerability affects not just individual devices but entire networks of interconnected smart TVs, creating a potential attack surface for broader network compromise. This weakness creates opportunities for attackers to establish persistent access points or use the devices as launching platforms for further attacks within the network infrastructure.
Mitigation strategies for CVE-2018-13989 should focus on implementing robust input validation and authentication controls at the device level. Network administrators should immediately disable unnecessary services running on TCP port 8085 and implement firewall rules to restrict access to this port from untrusted networks. The device firmware should be updated to include proper request origin verification and implement anti-CSRF tokens for each transaction. Additionally, organizations should consider network segmentation to isolate smart TV devices from critical business systems and implement monitoring solutions to detect unusual patterns of requests to the affected endpoint. According to ATT&CK framework, this vulnerability maps to T1210 - Exploitation of Remote Services and T1071.1 - Application Layer Protocol: Web Protocols, as it involves exploitation of web-based services and remote access capabilities. The vulnerability also relates to T1082 - System Information Discovery and T1069.1 - Access to Cloud Services, as attackers may use compromised devices to gather network information or access cloud-based services. Organizations should implement comprehensive vulnerability management programs to identify and remediate similar weaknesses in their smart device ecosystems.