CVE-2018-7300 in Homematic CCU2
Summary
by MITRE
Directory Traversal / Arbitrary File Write / Remote Code Execution in the User.setLanguage method in eQ-3 AG Homematic CCU2 2.29.2 and earlier allows remote attackers to write arbitrary files to the device's filesystem. This vulnerability can be exploited by unauthenticated attackers with access to the web interface.
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Analysis
by VulDB Data Team • 07/07/2024
The vulnerability identified as CVE-2018-7300 represents a critical directory traversal flaw affecting eQ-3 AG Homematic CCU2 devices running firmware versions 2.29.2 and earlier. This weakness resides within the User.setLanguage method implementation, creating a pathway for remote attackers to manipulate the device's file system through the web interface without requiring authentication. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly restrict file path operations, allowing malicious actors to navigate beyond intended directories and execute arbitrary file write operations.
The technical exploitation of this vulnerability leverages the lack of proper path validation in the setLanguage method, which accepts user-supplied language parameters without adequate sanitization. Attackers can construct malicious file paths that bypass normal directory restrictions, enabling them to write files to critical system locations including configuration files, executable scripts, and system binaries. This arbitrary file writing capability directly translates to remote code execution potential, as attackers can place malicious payloads in locations where the system will execute them during normal operation. The vulnerability operates at the application layer and affects the device's web-based management interface, making it accessible over standard HTTP/HTTPS protocols.
The operational impact of CVE-2018-7300 extends beyond simple unauthorized file operations, creating a complete compromise vector for attackers seeking persistent access to Homematic CCU2 devices. Once exploited, attackers can install backdoors, modify system configurations, and establish footholds within home automation networks that could serve as entry points for broader network infiltration. The vulnerability affects devices that form the central control hub for smart home environments, potentially allowing attackers to manipulate security systems, control connected devices, and access sensitive environmental data. This represents a significant risk in IoT environments where these devices often operate with minimal security monitoring and may lack network segmentation.
Security mitigations for CVE-2018-7300 require immediate firmware updates from eQ-3 AG to address the directory traversal and arbitrary file write vulnerabilities within the User.setLanguage method. Organizations should implement network segmentation to isolate Homematic CCU2 devices from critical network segments and apply strict firewall rules limiting access to the web interface to trusted IP addresses only. The vulnerability aligns with CWE-22 Directory Traversal and CWE-73 Path Traversal, both classified under the broader category of path manipulation weaknesses. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1078 Valid Accounts, as it enables remote code execution and potential account compromise. Device administrators should also consider implementing intrusion detection systems to monitor for suspicious file operations and network traffic patterns that may indicate exploitation attempts.