CVE-2019-9727 in Homematic CCU3
Summary
by MITRE
Unauthenticated password hash disclosure in the User.getUserPWD method in eQ-3 AG Homematic CCU3 3.43.15 and earlier allows remote attackers to retrieve the GUI password hashes of GUI users. This vulnerability can be exploited by unauthenticated attackers with access to the web interface.
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Analysis
by VulDB Data Team • 09/17/2023
The vulnerability identified as CVE-2019-9727 represents a critical security flaw in the eQ-3 AG Homematic CCU3 system version 3.43.15 and earlier. This issue resides within the User.getUserPWD method implementation, which exposes sensitive authentication data through an improperly secured web interface endpoint. The vulnerability specifically affects the graphical user interface authentication mechanism, allowing unauthorized actors to extract password hashes without requiring any prior authentication credentials. This represents a fundamental breakdown in the system's access control measures and authentication security architecture.
The technical exploitation of this vulnerability occurs through direct access to the web interface where the User.getUserPWD method is exposed. Attackers can simply make specific HTTP requests to retrieve the password hash values stored in the system's user database. The flaw stems from inadequate input validation and access control enforcement within the web application layer, where sensitive user authentication data is returned in plaintext format without proper authorization checks. This vulnerability falls under the CWE-200 category of Information Disclosure, specifically related to the exposure of sensitive authentication data. The attack vector is classified as network-based with minimal prerequisites, as no authentication is required to exploit the vulnerability.
The operational impact of CVE-2019-9727 extends beyond simple information disclosure, as password hashes provide attackers with the foundation for subsequent authentication attacks. Once obtained, these hashes can be subjected to offline password cracking attempts using tools like john the ripper or hashcat, potentially compromising user accounts and gaining unauthorized access to the Homematic CCU3 system. The vulnerability enables attackers to escalate privileges and potentially gain full administrative control over the smart home automation platform, affecting all connected devices and services managed through the compromised system. This represents a significant risk to home network security and privacy, as the compromised system could serve as a gateway for further lateral movement within the network infrastructure.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected Homematic CCU3 systems to version 3.43.16 or later, which contains the necessary security fixes. Network administrators should implement strict access controls and firewall rules to limit access to the web interface to trusted IP addresses only, while also monitoring for suspicious access patterns. Additionally, the system should be configured to enforce strong password policies and implement account lockout mechanisms to reduce the effectiveness of brute force attacks against retrieved password hashes. Security monitoring should include detection of unauthorized access attempts to the User.getUserPWD endpoint, and regular security audits should verify proper access control implementations. The vulnerability demonstrates the importance of proper input validation and access control enforcement in web applications, aligning with ATT&CK technique T1566 for credential access through network sniffing and information gathering. Organizations should also consider implementing multi-factor authentication mechanisms where possible to provide additional security layers beyond password-based authentication.