CVE-2017-14116 in U-verse
Summary
by MITRE
The AT&T U-verse 9.2.2h0d83 firmware for the Arris NVG599 device, when IP Passthrough mode is not used, configures WAN access to a caserver https service with the tech account and an empty password, which allows remote attackers to obtain root privileges by establishing a session on port 49955 and then installing new software, such as BusyBox with "nc -l" support.
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Analysis
by VulDB Data Team • 01/10/2021
The vulnerability identified as CVE-2017-14116 represents a critical authentication flaw in the AT&T U-verse firmware version 9.2.2h0d83 running on Arris NVG599 devices. This issue stems from improper credential handling within the WAN configuration process where the system defaults to using a hardcoded tech account with an empty password when IP Passthrough mode is disabled. The flaw creates a persistent security weakness that directly exposes administrative functions to unauthorized remote access, fundamentally undermining the device's network security posture. This vulnerability falls under CWE-255, which specifically addresses issues related to credentials management and authentication bypass mechanisms that allow attackers to gain unauthorized access to privileged functions.
The technical exploitation of this vulnerability occurs through a specific attack vector that leverages port 49955, which serves as the primary entry point for malicious actors to establish sessions with the compromised device. Once an attacker successfully connects to this port, they can execute arbitrary code and install malicious software packages such as BusyBox with netcat support, effectively gaining complete root access to the device. This privilege escalation allows the attacker to manipulate the device's core functionality, potentially leading to full network compromise and unauthorized data access. The attack chain demonstrates a classic privilege escalation vulnerability where weak authentication mechanisms enable attackers to progress from initial network access to complete system control, aligning with ATT&CK technique T1068 which covers local privilege escalation through weak authentication.
The operational impact of this vulnerability extends beyond individual device compromise to potentially affect entire network infrastructures. When multiple devices within a network are running the vulnerable firmware, attackers can establish a foothold that enables them to pivot between devices and escalate their access to other network segments. The empty password configuration creates a persistent backdoor that remains active until firmware is updated, making it particularly dangerous for enterprise environments where network monitoring may not detect the initial compromise. This vulnerability particularly affects residential gateway devices that often serve as primary network entry points, making them attractive targets for attackers seeking to establish persistent access to home or small office networks.
Mitigation strategies for this vulnerability require immediate firmware updates from AT&T and Arris to address the hardcoded credential issue. Network administrators should implement strict firewall rules to block access to port 49955 from external networks and monitor for unusual traffic patterns on this port. The recommended approach includes disabling IP Passthrough mode when not required, as this configuration changes the device's security posture significantly. Additionally, organizations should conduct comprehensive network audits to identify all affected devices and ensure proper credential management practices are implemented. The vulnerability highlights the importance of secure default configurations and proper authentication mechanisms, as outlined in industry standards such as NIST SP 800-53 controls that emphasize the need for secure configuration management and access control policies to prevent unauthorized system access and privilege escalation attacks.