CVE-2017-7639 in Proxy Server
Summary
by MITRE
QNAP NAS application Proxy Server through version 1.2.0 does not authenticate requests properly. Successful exploitation can lead to change of the settings of Proxy Server.
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Analysis
by VulDB Data Team • 03/21/2023
The vulnerability identified as CVE-2017-7639 affects the QNAP NAS application Proxy Server version 1.2.0 and earlier, representing a critical authentication flaw that undermines the security posture of network infrastructure devices. This issue stems from improper request validation within the proxy server component, creating a pathway for unauthorized modifications to critical network configuration parameters. The vulnerability falls under the category of weak authentication mechanisms and can be classified as CWE-287, which specifically addresses improper authentication issues in software systems. The affected QNAP NAS devices operate as network appliances that provide proxy services to manage and filter internet traffic, making them attractive targets for attackers seeking to compromise network security.
The technical flaw manifests through the absence of proper authentication checks when processing requests to modify proxy server settings. Attackers can exploit this weakness by sending crafted requests to the proxy server without providing valid credentials, thereby gaining the ability to alter configuration parameters such as proxy rules, access controls, and network filtering settings. This lack of authentication validation creates a scenario where any network entity can manipulate the proxy server functionality, potentially leading to man-in-the-middle attacks, unauthorized data access, or complete network traffic interception. The vulnerability specifically impacts the administrative interface of the proxy server component, allowing unauthorized modification of core network policies that control how internet traffic flows through the QNAP device.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to fundamentally alter network security configurations that protect enterprise environments. Successful exploitation could result in complete compromise of the network proxy functionality, allowing attackers to redirect traffic through malicious endpoints, bypass security controls, or establish persistent access points within the network infrastructure. This vulnerability directly relates to ATT&CK technique T1071.004, which covers application layer protocol tunneling, as attackers could leverage the proxy server to establish covert communication channels. Organizations using affected QNAP NAS devices face significant risk of network infiltration, as the proxy server becomes a potential entry point for broader network attacks, particularly in environments where these devices serve as network gateways or security appliances.
Mitigation strategies for CVE-2017-7639 require immediate implementation of firmware updates from QNAP to address the authentication flaw in the proxy server component. Organizations should also implement network segmentation to limit access to affected devices, deploy network monitoring solutions to detect unauthorized configuration changes, and establish strict access controls for proxy server administrative interfaces. Additional defensive measures include enabling network access control lists to restrict communication with the proxy server ports, implementing intrusion detection systems to monitor for suspicious administrative requests, and conducting regular security audits to verify proxy server configurations. The vulnerability demonstrates the critical importance of proper authentication mechanisms in network infrastructure devices and serves as a reminder of the need for comprehensive security testing of all administrative interfaces in enterprise network appliances.