CVE-2017-15626 in WVR
Summary
by MITRE
TP-Link WVR, WAR and ER devices allow remote authenticated administrators to execute arbitrary commands via command injection in the new-bindif variable in the pptp_server.lua file.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability CVE-2017-15626 represents a critical command injection flaw affecting TP-Link WVR, WAR, and ER series network devices. This vulnerability exists within the pptp_server.lua file where the new-bindif variable is improperly handled, allowing authenticated administrators to execute arbitrary commands remotely. The issue stems from insufficient input validation and sanitization of user-supplied parameters within the device's Point-to-Point Tunneling Protocol configuration interface. Security researchers identified that when administrators configure PPTP server settings through the web interface, the system fails to properly escape or validate the new-bindif parameter, creating a pathway for malicious command execution. This vulnerability specifically impacts devices running firmware versions that include the problematic pptp_server.lua script, making it a widespread concern across multiple TP-Link product lines.
The technical exploitation of this vulnerability occurs through the manipulation of the new-bindif parameter during PPTP server configuration. When an authenticated administrator accesses the web-based management interface and submits a crafted value for this parameter, the system directly incorporates the input into system commands without proper sanitization. This command injection flaw falls under CWE-77 which specifically addresses improper neutralization of special elements used in commands. Attackers can leverage this vulnerability to execute arbitrary system commands with the privileges of the web server process, potentially gaining full administrative control over the device. The authenticated nature of the attack means that only users with valid administrative credentials can exploit this flaw, but the impact remains severe as it allows for complete system compromise.
The operational impact of CVE-2017-15626 extends beyond simple privilege escalation to encompass complete device compromise and potential network infiltration. Once exploited, attackers can execute commands such as modifying system configurations, installing backdoors, accessing sensitive network data, or using the compromised device as a pivot point for attacking other network segments. This vulnerability directly maps to ATT&CK technique T1059 which describes the execution of commands through various interfaces including web shells and command-line utilities. The affected devices typically operate in network infrastructure roles, making them attractive targets for attackers seeking persistent access to corporate networks. Additionally, the vulnerability's presence in multiple device models increases the attack surface significantly, as it affects both wireless and wired network equipment from the same manufacturer. Organizations with these devices in production environments face potential data breaches, service disruptions, and regulatory compliance violations.
Mitigation strategies for CVE-2017-15626 require immediate firmware updates from TP-Link to address the command injection vulnerability in pptp_server.lua. Network administrators should also implement strict access controls and monitoring of administrative interfaces to detect suspicious command execution patterns. The vulnerability demonstrates the importance of input validation in web applications and highlights the need for proper security testing of network device firmware. Organizations should consider network segmentation to limit the potential impact of successful exploitation and implement intrusion detection systems that can identify command injection attempts. Additionally, regular security audits of network infrastructure components and maintaining up-to-date vulnerability assessments are essential practices for preventing exploitation of similar flaws. The vulnerability also underscores the necessity of following secure coding practices such as those outlined in the OWASP Top Ten and NIST cybersecurity guidelines for preventing command injection attacks in network devices.