CVE-2017-15632 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-mppeencryption variable in the pptp_server.lua file.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability identified as CVE-2017-15632 affects TP-Link WVR WAR and ER series devices, representing a critical command injection flaw that enables authenticated remote attackers to execute arbitrary code on affected systems. This vulnerability resides within the pptp_server.lua file where the new-mppeencryption variable is processed without adequate input validation or sanitization, creating a pathway for malicious command execution. The flaw specifically targets the Point-to-Point Tunneling Protocol (PPTP) server configuration functionality, making it particularly dangerous for network infrastructure devices that handle remote access protocols.
The technical implementation of this vulnerability follows a classic command injection pattern where user-supplied input is directly incorporated into system commands without proper escaping or validation. When an authenticated administrator accesses the PPTP server configuration interface and provides malicious input through the new-mppeencryption parameter, the system processes this input directly within shell commands, allowing attackers to inject additional commands that execute with the privileges of the web server process. This type of vulnerability maps directly to CWE-77 which categorizes command injection flaws, and aligns with ATT&CK technique T1059.001 for command and script injection. The authentication requirement does not mitigate the severity since administrators typically possess elevated privileges within the network infrastructure.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential network infiltration. An attacker who gains access to administrative credentials can leverage this vulnerability to escalate privileges, install backdoors, modify network configurations, or exfiltrate sensitive data from the affected devices. The PPTP protocol is commonly used for remote access, making these devices attractive targets for attackers seeking persistent network access. The vulnerability affects multiple TP-Link models including WVR, WAR, and ER series, suggesting a widespread impact across various enterprise and small business network deployments where these devices serve as critical infrastructure components.
Mitigation strategies for CVE-2017-15632 should prioritize immediate firmware updates from TP-Link to address the underlying command injection flaw in the pptp_server.lua file. Network administrators should implement network segmentation to limit access to these devices and restrict administrative access to trusted networks only. Additional protective measures include disabling PPTP protocol entirely if not required, implementing strict input validation for all web application parameters, and monitoring network traffic for suspicious command execution patterns. The vulnerability highlights the importance of secure coding practices and input validation in network device firmware, particularly when handling user-supplied parameters that may be passed to system commands. Organizations should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts targeting similar command injection vulnerabilities in their network infrastructure.