CVE-2019-19228 in Solar Inverter
Summary
by MITRE
Fronius Solar Inverter devices before 3.14.1 (HM 1.12.1) allow attackers to bypass authentication because the password for the today account is stored in the /tmp/web_users.conf file.
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Analysis
by VulDB Data Team • 03/07/2024
The vulnerability identified as CVE-2019-19228 affects Fronius Solar Inverter devices running firmware versions prior to 3.14.1, specifically impacting the HM 1.12.1 variant. This authentication bypass flaw represents a critical security weakness that undermines the device's access control mechanisms and exposes operational systems to unauthorized access. The vulnerability stems from improper credential storage practices within the device's configuration files, creating an exploitable condition that allows attackers to gain administrative privileges without proper authentication.
The technical implementation of this vulnerability involves the insecure storage of the password for the today account within the /tmp/web_users.conf file. This file location presents multiple security concerns as the /tmp directory is typically world-writable and accessible, making it an ideal target for privilege escalation attacks. The password is stored in plaintext format, eliminating any form of encryption or obfuscation that would normally protect sensitive credentials. This configuration violates fundamental security principles and creates a direct pathway for attackers to obtain administrative access to the solar inverter system.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential compromise of the entire solar energy infrastructure. Attackers who exploit this vulnerability can manipulate inverter settings, access sensitive operational data, and potentially disrupt energy generation processes. The implications are particularly severe for industrial and commercial solar installations where these devices form critical components of energy management systems. The vulnerability enables attackers to perform actions such as modifying configuration parameters, accessing real-time energy monitoring data, and potentially causing operational disruptions that could result in financial losses or safety hazards.
From a cybersecurity perspective, this vulnerability maps directly to CWE-312 (Sensitive Data in Memory) and CWE-522 (Insufficiently Protected Credentials) within the CWE catalog, highlighting the insecure handling of authentication credentials. The attack surface aligns with ATT&CK technique T1078.004 (Valid Accounts: Cloud Accounts) and T1566.001 (Phishing: Spearphishing Attachment) as attackers could potentially leverage this weakness to establish persistent access or escalate privileges within the network. The vulnerability also represents a failure in the principle of least privilege and proper access control implementation, as the system should not expose authentication credentials in easily accessible locations.
Mitigation strategies for this vulnerability require immediate firmware updates to version 3.14.1 or later, which address the insecure credential storage issue through proper encryption and access control mechanisms. Organizations should also implement network segmentation to limit access to these devices to authorized personnel only, and conduct thorough security audits of all connected systems to identify potential exploitation attempts. Regular monitoring of system logs for unauthorized access attempts and implementing intrusion detection systems can help identify exploitation activities. Additionally, security teams should consider disabling unnecessary administrative accounts and implementing multi-factor authentication mechanisms where possible to reduce the attack surface and provide additional protection layers against similar vulnerabilities.