CVE-2017-15627 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-pns variable in the pptp_client.lua file.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability CVE-2017-15627 represents a critical command injection flaw affecting TP-Link WVR, WAR, and ER series network devices. This security weakness resides within the pptp_client.lua configuration file where the new-pns variable fails to properly sanitize user input, creating an avenue for malicious actors to execute arbitrary commands on affected systems. The vulnerability specifically targets authenticated administrators who possess valid credentials, making it particularly dangerous as it leverages legitimate administrative access to escalate privileges and gain unauthorized control over network infrastructure. The affected devices operate within enterprise and small business environments where PPTP (Point-to-Point Tunneling Protocol) client functionality is utilized for remote access connections, making this flaw especially concerning for organizations relying on such networking solutions.
From a technical perspective, the vulnerability manifests as a classic command injection vulnerability categorized under CWE-77, which occurs when user-supplied data is directly incorporated into system commands without proper validation or escaping mechanisms. The new-pns variable in the pptp_client.lua file serves as the injection point where unfiltered input from authenticated administrators can be manipulated to include malicious command sequences. When the system processes this variable during PPTP client configuration, the unsanitized input gets executed as shell commands, potentially allowing attackers to gain root-level access to the device's operating system. This type of vulnerability falls under the ATT&CK framework's technique T1059.001 for Command and Scripting Interpreter, specifically targeting shell commands execution within the device's environment. The exploitation requires an authenticated administrative session, but once achieved, the attacker can execute any command available to the system's privileged user context, potentially leading to complete device compromise.
The operational impact of CVE-2017-15627 extends beyond simple unauthorized command execution, as it fundamentally undermines the security posture of affected networks. Organizations using these TP-Link devices face significant risks including unauthorized network access, data exfiltration, and potential use as a pivot point for lateral movement within the network infrastructure. The vulnerability affects devices that typically serve as network gateways and remote access points, making them prime targets for attackers seeking persistent access to corporate networks. When exploited, the vulnerability can lead to complete device compromise, allowing attackers to modify network configurations, install backdoors, or establish persistent access mechanisms. The impact is particularly severe in environments where these devices are used for remote employee access or site-to-site VPN connections, as the compromise of such infrastructure can result in widespread network infiltration and data breaches.
Mitigation strategies for CVE-2017-15627 primarily focus on immediate firmware updates provided by TP-Link, which address the command injection vulnerability through proper input validation and sanitization of the new-pns variable. Network administrators should prioritize applying vendor patches as soon as they become available, as the vulnerability does not require special exploitation tools and can be readily exploited by threat actors with basic knowledge of command injection techniques. Additional defensive measures include implementing strict access controls to limit administrative privileges, monitoring network traffic for suspicious command execution patterns, and conducting regular security assessments of network infrastructure. Organizations should also consider network segmentation to limit the potential impact of device compromise and implement intrusion detection systems to monitor for unusual administrative activities. The vulnerability serves as a reminder of the critical importance of proper input validation in network device software development and the necessity of regular security updates to protect against known command injection vulnerabilities that could be exploited by adversaries to gain unauthorized access to network infrastructure.