CVE-2015-7251 in ZXHN H108N R1A
Summary
by MITRE
ZTE ZXHN H108N R1A devices before ZTE.bhs.ZXHNH108NR1A.k_PE have a hardcoded password of root for the root account, which allows remote attackers to obtain administrative access via a TELNET session.
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Analysis
by VulDB Data Team • 12/07/2024
The CVE-2015-7251 vulnerability affects ZTE ZXHN H108N R1A devices running firmware versions prior to ZTE.bhs.ZXHNH108NR1A.k_PE. This critical security flaw represents a classic case of hardcoded credentials that fundamentally undermines the device's authentication mechanisms. The vulnerability specifically targets the root account which is configured with a default password of "root" that cannot be changed or removed through normal administrative procedures. This hardcoded credential configuration creates an inherent backdoor that persists across device reboots and firmware updates, making it particularly dangerous for long-term deployments.
The technical exploitation of this vulnerability occurs through unencrypted TELNET sessions, which exposes the device to remote attackers without requiring any sophisticated attack vectors or prior knowledge of the system. TELNET protocol operates in plaintext, meaning that credentials transmitted over the network can be easily intercepted through network sniffing techniques. This vulnerability aligns with CWE-798, which specifically addresses the use of hardcoded passwords and credentials in software systems. The flaw demonstrates poor security engineering practices where default credentials are not only hardcoded but also remain unchanged throughout the device's operational lifecycle, violating fundamental security principles of least privilege and dynamic credential management.
From an operational impact perspective, this vulnerability enables attackers to achieve complete administrative control over affected devices, potentially leading to full network compromise. Once an attacker gains access through the hardcoded root credentials, they can modify device configurations, install malicious software, monitor network traffic, and use the device as a pivot point for attacking other systems within the network. The vulnerability affects a specific model of residential gateway and fiber optic network equipment, which are commonly deployed in both residential and small business environments. This creates a significant risk for organizations that rely on these devices for network connectivity, as they may unknowingly provide attackers with persistent access to their network infrastructure.
The attack surface for this vulnerability extends beyond simple remote access, as compromised devices can serve as entry points for broader network infiltration activities. According to ATT&CK framework, this vulnerability maps to T1078 Valid Accounts, where attackers leverage default credentials to establish persistent access to target systems. The lack of proper authentication mechanisms also relates to T1110 Brute Force, as attackers could potentially use automated tools to guess or exploit the hardcoded credentials. Organizations should consider implementing network segmentation to limit the potential impact of such compromises and deploy network monitoring solutions to detect unauthorized TELNET connections to affected devices. The vulnerability highlights the critical importance of firmware update management and the need for manufacturers to provide regular security patches for their products, particularly in the context of IoT and network infrastructure devices that often operate with minimal oversight.
Mitigation strategies should include immediate firmware updates to the latest available versions that address this hardcoded credential issue. Network administrators should disable TELNET services and implement SSH as a secure alternative for remote device management. Additionally, implementing network access controls and monitoring for unauthorized TELNET connections can help detect exploitation attempts. The vulnerability underscores the necessity of conducting regular security assessments of network infrastructure devices and maintaining up-to-date inventory of all connected equipment to ensure timely patch deployment.