CVE-2017-14115 in U-verse
Summary
by MITRE
The AT&T U-verse 9.2.2h0d83 firmware for the Arris NVG589 and NVG599 devices, when IP Passthrough mode is not used, configures ssh-permanent-enable WAN SSH logins to the remotessh account with the 5SaP9I26 password, which allows remote attackers to access a "Terminal shell v1.0" service, and subsequently obtain unrestricted root privileges, by establishing an SSH session and then entering certain shell metacharacters and BusyBox commands.
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Analysis
by VulDB Data Team • 01/10/2021
The vulnerability identified as CVE-2017-14115 affects AT&T U-verse gateway devices running firmware version 9.2.2h0d83, specifically the Arris NVG589 and NVG599 models. This security flaw exists within the device's default configuration when IP Passthrough mode is disabled, creating a persistent backdoor that compromises the device's security posture. The vulnerability represents a critical misconfiguration that exposes administrative services without proper authentication mechanisms, allowing unauthorized access to the device's underlying system.
The technical flaw manifests through the improper configuration of SSH services on these devices, where the ssh-permanent-enable feature is automatically enabled without requiring proper authentication. The remotessh account is configured with a hardcoded password of 5SaP9I26, which is a well-known default credential that has been documented in various security databases and penetration testing resources. This hardcoded credential creates a persistent access vector that remains unchanged regardless of device updates or configuration changes, making it particularly dangerous for long-term deployments.
When an attacker establishes an SSH session using the default credentials, they gain access to a "Terminal shell v1.0" service that provides command execution capabilities. The vulnerability becomes particularly severe because the attacker can leverage shell metacharacters and BusyBox commands to escalate privileges from the initial SSH session to unrestricted root access. This privilege escalation occurs through the exploitation of shell command injection vulnerabilities within the device's command processing mechanisms, allowing attackers to execute arbitrary commands with the highest possible system privileges.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables complete system compromise and potential lateral movement within networks. Network administrators who deploy these devices without properly configuring or disabling the SSH service create an attack surface that can be exploited by both skilled attackers and automated scanning tools. The vulnerability affects devices that are typically deployed in residential and small business environments where security monitoring and patch management may be limited, making the exploitation more likely and potentially devastating.
Organizations should implement immediate mitigation strategies including disabling the SSH service when not required, changing default credentials to strong, unique passwords, and implementing network segmentation to limit access to these devices. The vulnerability aligns with CWE-798, which addresses the use of hardcoded credentials, and maps to ATT&CK technique T1078.004 for valid accounts and T1059.004 for scripting through shell commands. Regular security audits and network monitoring should be implemented to detect unauthorized access attempts and ensure that default configurations are not left in place.
This vulnerability demonstrates the critical importance of proper device hardening and the dangers of leaving default services enabled with known credentials. The persistence of hardcoded passwords in firmware implementations highlights the need for comprehensive security testing of network devices and regular security assessments to identify and remediate similar configuration flaws across all network infrastructure components.