CVE-2018-7298 in Homematic CCU2
Summary
by MITRE
In /usr/local/etc/config/addons/mh/loopupd.sh on eQ-3 AG HomeMatic CCU2 2.29.22 devices, software update packages are downloaded via the HTTP protocol, which does not provide any cryptographic protection of the downloaded contents. An attacker with a privileged network position (which could be obtained via DNS spoofing of www.meine-homematic.de or other approaches) can exploit this issue in order to provide arbitrary malicious firmware updates to the CCU2. This can result in a full system compromise.
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Analysis
by VulDB Data Team • 01/08/2020
The vulnerability identified as CVE-2018-7298 affects the eQ-3 AG HomeMatic CCU2 device running firmware version 2.29.22 and specifically targets the loopupd.sh script located in the /usr/local/etc/config/addons/mh/ directory. This represents a critical security flaw in the device's update mechanism that undermines the integrity and authenticity of software updates. The vulnerability stems from the use of unencrypted HTTP protocol for downloading software packages, creating a fundamental weakness in the device's security architecture. The absence of cryptographic protection during the update process means that downloaded content can be intercepted, modified, or replaced without detection by the receiving device.
The technical implementation of this vulnerability allows an attacker with a privileged network position to perform man-in-the-middle attacks against the update process. This can be achieved through various means including DNS spoofing of the legitimate update server at www.meine-homematic.de or other network-based attacks that position the attacker between the device and the update source. The attack vector exploits the lack of integrity verification mechanisms and cryptographic signatures that should normally validate the authenticity of downloaded firmware. The vulnerability directly maps to CWE-319 - Cleartext Transmission of Sensitive Information, which specifically addresses the transmission of confidential information without adequate encryption or protection mechanisms. This weakness enables attackers to inject malicious code or firmware into the update process, potentially compromising the entire device.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential lateral movement within affected networks. Once an attacker successfully injects malicious firmware, they gain full control over the CCU2 device, which serves as a central hub for HomeMatic home automation systems. This compromise can lead to unauthorized access to connected smart home devices, potential data exfiltration, and the ability to manipulate home automation systems for malicious purposes. The attack can result in persistent backdoors within the network infrastructure, as the compromised device can be used as a foothold for further attacks. This vulnerability also aligns with ATT&CK technique T1072 - Software Deployment Tools, where attackers use legitimate software deployment mechanisms to execute malicious code. The compromised device could potentially be used to attack other networked devices or serve as a command and control point for broader network infiltration.
Mitigation strategies for CVE-2018-7298 should focus on implementing secure update mechanisms and network-level protections. Organizations should immediately implement network segmentation to isolate critical devices from untrusted network segments and deploy DNS security measures including DNSSEC to prevent DNS spoofing attacks. The most effective immediate solution involves upgrading to firmware versions that implement HTTPS for update downloads and include cryptographic signature verification of update packages. Network administrators should also consider implementing intrusion detection systems to monitor for unusual update activity and establish secure communication channels using TLS encryption for all update communications. Additionally, implementing certificate pinning mechanisms and regular security audits of update processes can help prevent similar vulnerabilities in the future. The vulnerability highlights the importance of secure boot processes and the necessity of implementing proper cryptographic protections for all device communications, particularly those involving firmware updates and system modifications.