CVE-2020-25752 in Envoy
Summary
by MITRE • 06/17/2021
An issue was discovered on Enphase Envoy R3.x and D4.x devices. There are hardcoded web-panel login passwords for the installer and Enphase accounts. The passwords for these accounts are hardcoded values derived from the MD5 hash of the username and serial number mixed with some static strings. The serial number can be retrieved by an unauthenticated user at /info.xml. These passwords can be easily calculated by an attacker; users are unable to change these passwords.
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Analysis
by VulDB Data Team • 06/21/2021
This vulnerability affects Enphase Envoy R3.x and D4.x solar energy monitoring devices, representing a critical security flaw that undermines the fundamental authentication mechanisms of these industrial IoT systems. The issue stems from the implementation of hardcoded credentials that are embedded within the device firmware, creating a persistent backdoor access vector that persists across device reboots and updates. The vulnerability is particularly concerning because it affects both installer and Enphase accounts, which are typically privileged access points for system configuration and monitoring functions. The hardcoded nature of these credentials means that once an attacker discovers the password calculation methodology, they can gain unauthorized access to critical system functions without requiring any legitimate authentication.
The technical implementation of this vulnerability involves a predictable password derivation algorithm that combines the device serial number with username information through MD5 hashing. The serial number is exposed through an unauthenticated endpoint at /info.xml, making it trivial for any attacker to obtain the necessary information to compute the passwords. This design flaw follows the pattern described in CWE-259, which addresses the use of hard-coded passwords, and demonstrates poor security practices in credential management. The attack vector is particularly dangerous because it requires no prior authentication or network access, making it an ideal target for reconnaissance and initial access phases. The combination of exposed serial numbers and predictable password generation creates a scenario where an attacker can easily calculate valid credentials for multiple accounts without any legitimate user interaction or system compromise.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential system compromise, data exfiltration, and disruption of solar energy monitoring operations. Attackers can exploit these hardcoded credentials to modify system configurations, access sensitive operational data, or potentially disrupt energy production monitoring functions that are critical for grid stability and system maintenance. The inability for users to change these passwords compounds the risk, as organizations cannot remediate the issue through standard password management procedures. This vulnerability directly impacts the security posture of distributed energy systems and represents a significant concern for industrial control systems security, aligning with ATT&CK technique T1078.004 which covers legitimate credentials and T1566.001 for credential access through network sniffing and credential dumping. The long-term implications include potential for lateral movement within networked solar installations and the possibility of cascading security failures across interconnected systems.
Organizations should immediately implement network segmentation to isolate affected devices from critical network segments, disable unnecessary services and ports, and consider deploying network monitoring solutions to detect unauthorized access attempts. The most effective immediate mitigation involves replacing affected devices with versions that implement proper credential management, as the hardcoded nature of these passwords means that standard security updates cannot resolve the issue. Network administrators should also conduct comprehensive inventory audits to identify all affected devices and implement temporary access controls through firewall rules or network access control lists. The vulnerability highlights the importance of secure credential management practices and demonstrates the risks associated with embedded systems that do not follow secure development lifecycle principles. Long-term security improvements should focus on implementing dynamic credential generation, secure boot processes, and proper authentication mechanisms that prevent the use of hardcoded credentials in production systems.