CVE-2019-10119 in Homematic
Summary
by MITRE
eQ-3 HomeMatic CCU2 devices before 2.41.8 and CCU3 devices before 3.43.16 use session IDs for authentication but lack authorization checks. An attacker can obtain a session ID via an invalid login attempt to the RemoteApi account, aka HMCCU-154. This leads to automatic login as admin.
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Analysis
by VulDB Data Team • 10/24/2023
The vulnerability identified as CVE-2019-10119 affects eQ-3 HomeMatic CCU2 and CCU3 home automation devices, representing a critical authentication flaw that undermines the security posture of these industrial control systems. This issue stems from improper session management where the devices generate session IDs for user authentication but fail to implement adequate authorization checks to verify user privileges before granting access. The flaw specifically impacts firmware versions prior to 2.41.8 for CCU2 devices and 3.43.16 for CCU3 devices, creating a persistent security weakness that has affected numerous installations in residential and commercial environments.
The technical exploitation of this vulnerability occurs through a specific attack vector involving invalid login attempts to the RemoteApi account. When an attacker performs an invalid login attempt, the system generates a session ID that can be captured and subsequently used by the attacker to gain administrative access to the device without proper authentication. This represents a classic session management weakness that aligns with CWE-613, which addresses inadequate session management and the exposure of session identifiers. The vulnerability essentially creates a backdoor access mechanism where the session ID obtained through a failed authentication attempt becomes a valid credential for administrative access, bypassing the normal authentication process entirely.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it allows attackers to assume full administrative privileges over the HomeMatic control systems. This level of access enables malicious actors to modify device configurations, access sensitive data, manipulate automation rules, and potentially disrupt the entire home automation ecosystem. The implications are particularly concerning in commercial settings where these devices control critical building systems, lighting, heating, and security mechanisms. From an ATT&CK framework perspective, this vulnerability maps to T1078 Valid Accounts and T1566 Phishing, as it exploits legitimate authentication mechanisms to gain unauthorized access, while also representing a privilege escalation vector that could lead to further system compromise.
Organizations and users affected by this vulnerability should immediately implement firmware updates to versions 2.41.8 for CCU2 devices and 3.43.16 for CCU3 devices to address the authentication bypass issue. Network segmentation should be implemented to isolate these devices from critical network segments, and access controls should be strengthened to limit who can interact with the RemoteApi interface. Additionally, monitoring should be enhanced to detect unusual login patterns or session activity that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper authorization checks in authentication systems and highlights how seemingly minor flaws in session management can create significant security risks in embedded IoT devices. Security teams should conduct comprehensive assessments of their HomeMatic deployments to identify affected devices and ensure proper patch management protocols are in place to prevent similar vulnerabilities from occurring in other embedded systems.