CVE-2017-15619 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 pptphellointerval variable in the pptp_client.lua file.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability identified as CVE-2017-15619 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_client.lua file where the pptphellointerval variable is improperly handled, creating a pathway for malicious command execution. The flaw specifically targets the Point-to-Point Tunneling Protocol (PPTP) client implementation within these network devices, making it particularly dangerous for organizations relying on PPTP connectivity for remote access or site-to-site connections.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the device's web interface configuration handling. When an authenticated administrator modifies PPTP client settings through the web management interface, the system fails to properly escape or validate the pptphellointerval parameter before incorporating it into system commands. This classic command injection vulnerability allows attackers who have gained administrative credentials to craft malicious input that gets executed as shell commands on the underlying operating system. The vulnerability maps directly to CWE-77 and CWE-94, which classify it as a command injection flaw and a code injection vulnerability respectively, with the specific implementation involving improper neutralization of special elements used in command execution.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the affected network devices. Once exploited, adversaries can execute arbitrary commands with the privileges of the web server process, which typically runs with elevated system permissions. This enables a wide range of malicious activities including but not limited to network reconnaissance, data exfiltration, lateral movement within the network, and installation of persistent backdoors. The vulnerability is particularly concerning because it requires only authenticated administrative access, which means that an attacker who has already compromised administrative credentials or gained access through other means can immediately leverage this flaw to escalate their privileges and gain complete system control. According to ATT&CK framework, this vulnerability aligns with T1059.001 (Command and Scripting Interpreter) and T1068 (Local Privilege Escalation) techniques, as it allows for command execution and privilege escalation within the device's operating environment.
Organizations affected by this vulnerability should implement immediate mitigations including applying the latest firmware updates from TP-Link, which typically contain patches addressing the command injection flaw in the pptp_client.lua file. Network segmentation and access control measures should be strengthened to limit administrative access to these devices, ensuring that only authorized personnel have the necessary credentials. Additionally, monitoring for unusual command execution patterns and implementing network-based intrusion detection systems can help identify exploitation attempts. The vulnerability also highlights the importance of input validation and secure coding practices in embedded network devices, emphasizing that even administrative interfaces require robust sanitization of user inputs to prevent command injection attacks. Organizations should conduct comprehensive vulnerability assessments to identify similar flaws in other network infrastructure devices and ensure that all firmware and software components are regularly updated to address known security vulnerabilities.