CVE-2017-15628 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 lcpechointerval variable in the pptp_server.lua file.
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Analysis
by VulDB Data Team • 01/29/2021
The vulnerability identified as CVE-2017-15628 affects TP-Link WVR WAR and ER series devices, representing a critical command injection flaw that enables remote authenticated administrators to execute arbitrary code on affected systems. This vulnerability resides within the pptp_server.lua file where the lcpechointinterval variable is processed without proper input sanitization, creating a pathway for malicious command execution. The flaw specifically targets the PPTP (Point-to-Point Tunneling Protocol) server implementation within these network devices, which are commonly deployed in enterprise and small office environments for remote access and VPN connectivity. The vulnerability's severity is amplified by the fact that it requires only authenticated administrative access, making it particularly dangerous as it can be exploited by compromised accounts or insider threats.
The technical exploitation of this vulnerability follows a command injection pattern that aligns with CWE-77 and CWE-89, where user-supplied input is directly incorporated into system commands without adequate validation or escaping mechanisms. When an authenticated administrator modifies the lcpechointerval parameter through the device's web interface or API, the malicious input gets processed by the lua interpreter and subsequently passed to underlying shell commands without proper sanitization. This creates a classic command injection scenario where crafted input can be interpreted as shell commands rather than simple parameter values, potentially allowing attackers to execute arbitrary system commands with the privileges of the affected service account.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with full system control over the affected TP-Link devices. Successful exploitation could enable attackers to install malware, modify network configurations, establish persistent backdoors, or use the device as a pivot point for attacking other systems within the network infrastructure. The vulnerability affects devices that support PPTP VPN functionality, which may be used for remote employee access, site-to-site connections, or other critical network services. Network administrators who rely on these devices for secure remote access may find their security posture significantly compromised, as the vulnerability allows for complete system compromise without requiring additional attack vectors or elevated privileges.
Mitigation strategies for CVE-2017-15628 should prioritize immediate firmware updates from TP-Link, as the vendor likely released patches addressing the command injection vulnerability in the pptp_server.lua file. Organizations should implement network segmentation to limit access to these devices, restrict administrative access to only necessary personnel, and employ strict access controls including multi-factor authentication for administrative accounts. Security monitoring should include detection of unusual parameter modifications in PPTP-related configurations, and network traffic analysis should be employed to identify potential exploitation attempts. The vulnerability's classification under ATT&CK technique T1059.001 (Command and Scripting Interpreter) indicates that defensive measures should focus on input validation, privilege separation, and comprehensive logging of administrative activities. Additionally, implementing network access controls and regular security audits can help prevent unauthorized access to administrative interfaces and reduce the attack surface for similar vulnerabilities in other components of the network infrastructure.