CVE-2018-15557 in Actiontec WEB6000Q
Summary
by MITRE
An issue was discovered in the Quantenna WiFi Controller on Telus Actiontec WEB6000Q v1.1.02.22 devices. An attacker can statically set his/her IP to anything on the 169.254.1.0/24 subnet, and obtain root access by connecting to 169.254.1.2 port 23 with telnet/netcat.
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Analysis
by VulDB Data Team • 10/08/2023
The vulnerability identified as CVE-2018-15557 represents a critical security flaw in the Quantenna WiFi Controller firmware running on Telus Actiontec WEB6000Q v1.1.02.22 devices. This issue stems from improper network configuration and weak authentication mechanisms within the embedded system. The vulnerability allows an attacker to exploit a misconfigured network interface that permits static IP assignment within the 169.254.1.0/24 subnet, which is typically reserved for link-local addressing. This misconfiguration creates an unexpected attack surface where malicious actors can manipulate their network presence to gain unauthorized system access. The root cause of this vulnerability aligns with CWE-284, which describes improper access control, and specifically relates to inadequate network segmentation and privilege management within embedded systems. The device's failure to properly validate IP address assignments within the link-local range demonstrates a fundamental flaw in network security implementation that directly impacts the device's overall security posture.
The technical exploitation of this vulnerability occurs through a straightforward yet effective method involving network manipulation and service exploitation. An attacker simply needs to configure their device to use an IP address within the 169.254.1.0/24 subnet, specifically targeting the IP address 169.254.1.2. Once this network configuration is established, the attacker can connect to port 23 using standard telnet or netcat tools to establish a connection to the device's telnet service. This telnet service is configured with weak authentication or default credentials that allow immediate root access to the system. The exploitation pathway follows the ATT&CK technique T1021.004 for remote services and T1078 for valid accounts, as it leverages an unsecured network service with default credentials. The vulnerability essentially provides a backdoor access method that bypasses normal authentication procedures and directly grants administrative privileges to any attacker who can reach the device through the configured network interface.
The operational impact of this vulnerability extends far beyond simple network access, as it provides complete system compromise and potential lateral movement within affected networks. Once an attacker gains root access through this vulnerability, they can execute arbitrary code, modify system configurations, extract sensitive data, and potentially use the compromised device as a pivot point for attacking other systems within the network. The implications are particularly severe in enterprise environments where these devices may be connected to critical network segments or where they serve as gateways to other network resources. The vulnerability affects not only the immediate device but also represents a potential vector for broader network compromise, as the compromised device could be used to launch further attacks or to serve as a persistent access point. This type of vulnerability directly violates the principle of least privilege and creates an uncontrolled entry point that could lead to significant data breaches, service disruptions, or compliance violations.
Mitigation strategies for CVE-2018-15557 should focus on immediate network-level protections combined with firmware updates and configuration hardening. Organizations should implement network segmentation to isolate affected devices from critical network segments and restrict access to the 169.254.1.0/24 subnet through firewall rules and access control lists. The telnet service should be disabled or configured with strong authentication mechanisms, and if telnet is required, it should be restricted to specific IP addresses or implemented with SSH as a more secure alternative. Network administrators should also validate that devices are not configured to accept arbitrary IP addresses within link-local ranges and should implement proper network monitoring to detect anomalous network behavior. The remediation process should include firmware updates from the vendor to address the underlying configuration issues, and organizations should conduct thorough vulnerability assessments to identify other potentially affected devices. Additionally, implementing network access control policies, regular security audits, and maintaining up-to-date network documentation can help prevent similar vulnerabilities from being introduced in the future. These measures align with the NIST Cybersecurity Framework and provide comprehensive protection against similar network-level privilege escalation attacks.