CVE-2019-10121 in Homematic CCU2
Summary
by MITRE
eQ-3 HomeMatic CCU2 devices before 2.41.8 and CCU3 devices before 3.43.15 use session IDs for authentication but lack authorization checks. An attacker can obtain a session ID via the user authentication dialogue, aka HMCCU-153. This leads to automatic login as admin.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/24/2023
The vulnerability identified as CVE-2019-10121 affects eQ-3 HomeMatic CCU2 and CCU3 home automation devices, representing a critical authentication flaw that undermines the security model of these industrial control systems. These devices are widely deployed in residential and commercial environments for home automation and building control, making their security implications particularly significant. The vulnerability stems from improper implementation of session management mechanisms where session identifiers are generated and used for authentication purposes without adequate authorization validation. This weakness creates a pathway for malicious actors to escalate privileges and gain administrative access to critical home automation infrastructure.
The technical flaw manifests in the authentication process where attackers can capture valid session IDs through the user authentication dialogue mechanism. This vulnerability falls under the category of insufficient authorization checks as defined by CWE-285, where the system fails to properly verify that authenticated users have appropriate access rights for the requested operations. The session management implementation lacks the necessary controls to ensure that session identifiers cannot be used by unauthorized parties to assume administrative privileges. The authentication dialogue serves as an attack surface where session tokens are exposed, allowing threat actors to leverage captured identifiers for unauthorized access.
The operational impact of this vulnerability is severe and multifaceted, as it enables full administrative control over affected HomeMatic devices without requiring knowledge of valid credentials. An attacker who successfully obtains a session ID can automatically log in as an administrator, gaining complete control over the device configuration, access to connected automation systems, and potentially compromising the entire home network infrastructure. This vulnerability aligns with ATT&CK technique T1078.004 which covers valid accounts and T1566.002 which involves spearphishing with links. The compromised devices become potential entry points for lateral movement within the network and could be used to facilitate further attacks against connected IoT devices and systems.
Mitigation strategies should focus on immediate firmware updates to versions 2.41.8 for CCU2 devices and 3.43.15 for CCU3 devices, which address the session management flaws. Network segmentation and access controls should be implemented to limit exposure of these devices to untrusted networks. Additionally, monitoring for unusual authentication patterns and session activity can help detect potential exploitation attempts. Organizations should also consider implementing multi-factor authentication mechanisms where available and regularly review access controls to ensure that only authorized personnel maintain administrative privileges on these critical infrastructure components. The vulnerability demonstrates the importance of proper session management and authorization checks in embedded systems, particularly those controlling physical environments and security infrastructure.