CVE-2019-5071 in AC9 Router AC1200
Summary
by MITRE
An exploitable command injection vulnerability exists in the /goform/WanParameterSetting functionality of Tenda AC9 Router AC1200 Smart Dual-Band Gigabit WiFi Route (AC9V1.0 Firmware V15.03.05.16multiTRU). A specially crafted HTTP POST request can cause a command injection in the DNS1 post parameters, resulting in code execution. An attacker can send HTTP POST request with command to trigger this vulnerability.
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Analysis
by VulDB Data Team • 02/26/2024
The CVE-2019-5071 vulnerability represents a critical command injection flaw within the Tenda AC9 router's web interface functionality. This vulnerability specifically affects the /goform/WanParameterSetting endpoint, which handles WAN parameter configuration through HTTP POST requests. The flaw resides in the improper validation and sanitization of user-supplied input within the DNS1 parameter, allowing attackers to inject arbitrary commands that execute with the privileges of the web server process. The vulnerability is particularly concerning because it affects a widely deployed consumer-grade router model that serves as a primary network gateway for numerous households and small businesses. The affected firmware version V15.03.05.16multiTRU demonstrates a clear lack of input validation controls that would normally prevent such injection attacks.
The technical exploitation of this vulnerability leverages the router's web administration interface to send specially crafted HTTP POST requests containing malicious command sequences within the DNS1 parameter. When the router processes this input without proper sanitization, the injected commands are executed within the router's operating environment, potentially allowing full system compromise. This type of vulnerability maps directly to CWE-77, which defines command injection as a weakness where user-supplied data is directly incorporated into shell commands without proper validation or escaping. The attack vector is straightforward since it requires only an HTTP POST request to the vulnerable endpoint, making it accessible to attackers with minimal technical expertise. The vulnerability's impact extends beyond simple command execution, as it can potentially allow attackers to modify router configurations, access network traffic, or establish persistent backdoors within the network infrastructure.
The operational implications of this vulnerability are severe for network security and privacy. As a router-level vulnerability, it provides attackers with privileged access to the local network, enabling them to monitor traffic, redirect connections, or even gain access to connected devices. The compromised router can serve as a pivot point for lateral movement within the network, potentially allowing attackers to access sensitive systems or data that would otherwise be isolated from direct internet exposure. This vulnerability also aligns with ATT&CK technique T1059.001 for command and scripting interpreter, specifically shell scripting, and represents a significant threat to network integrity and confidentiality. The impact is particularly severe in enterprise environments where these consumer routers are often deployed without proper security hardening, creating potential attack surfaces that could lead to broader security breaches.
Mitigation strategies for CVE-2019-5071 should focus on both immediate remediation and long-term security improvements. The primary recommendation involves updating to the latest firmware version provided by Tenda, which should contain proper input validation and sanitization controls for the affected parameters. Network administrators should also implement additional security measures such as restricting access to router administration interfaces from untrusted networks, implementing firewall rules to limit HTTP access to these endpoints, and conducting regular security assessments of network devices. The vulnerability highlights the importance of input validation at multiple levels within network infrastructure devices, as recommended by the OWASP Top Ten and NIST cybersecurity guidelines. Organizations should also consider implementing network segmentation and monitoring solutions to detect unusual traffic patterns that might indicate exploitation attempts, while maintaining regular patch management processes to address similar vulnerabilities in other network infrastructure components.