CVE-2017-7635 in Proxy Server
Summary
by MITRE
QNAP NAS application Proxy Server through version 1.2.0 does not utilize CSRF protections.
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Analysis
by VulDB Data Team • 02/13/2020
The QNAP NAS application Proxy Server vulnerability CVE-2017-7635 represents a critical security flaw in the web-based administration interface of QNAP Network Attached Storage devices. This vulnerability specifically affects versions 1.2.0 and earlier of the Proxy Server application, which is commonly installed on QNAP NAS systems to provide web proxy functionality. The flaw stems from the absence of Cross-Site Request Forgery (CSRF) protection mechanisms within the application's web interface, creating a significant attack vector that allows malicious actors to exploit the system's administrative functions without proper authorization. The vulnerability is categorized under CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses in web applications, making it a well-documented and serious security concern that has been recognized by the Common Weakness Enumeration project.
The technical implementation of this vulnerability occurs through the manipulation of web requests within the context of an authenticated session. When administrators interact with the Proxy Server web interface, the application fails to validate that requests originate from legitimate administrative sources rather than malicious third-party websites. An attacker can craft specially designed web pages or exploit existing social engineering techniques to trick authenticated users into performing administrative actions without their knowledge. This occurs because the application does not implement anti-CSRF tokens, referer validation, or other protective measures that would normally prevent unauthorized requests from being processed. The vulnerability essentially allows attackers to execute administrative commands such as modifying proxy settings, adding new users, or changing system configurations through the victim's authenticated browser session, making it particularly dangerous in enterprise environments where administrative privileges are commonly used.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with persistent access to critical network infrastructure components. Once exploited, attackers can modify proxy server configurations to redirect traffic through malicious servers, potentially enabling man-in-the-middle attacks or data exfiltration. The attack surface is particularly concerning given that QNAP NAS devices are commonly deployed in both corporate and home environments where they serve as central storage and network services platforms. The vulnerability can be exploited remotely without requiring any special privileges or authentication credentials, making it an attractive target for automated exploitation campaigns. This weakness directly impacts the CIA triad by compromising both confidentiality and integrity of network traffic passing through the compromised proxy server, as well as potentially affecting availability if attackers choose to disrupt proxy services or manipulate network routing.
Organizations affected by this vulnerability should implement immediate mitigations including updating to QNAP firmware versions that address this CSRF weakness, which typically involves applying patches that introduce proper anti-CSRF token validation. Network segmentation and access control measures should be implemented to limit exposure of administrative interfaces to trusted networks only, while also ensuring that administrative access is restricted to authorized personnel through multi-factor authentication. Security monitoring should be enhanced to detect anomalous proxy server configuration changes that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1078 which covers Valid Accounts and T1566 which covers Phishing, as it leverages legitimate administrative sessions to execute malicious actions. Additionally, this vulnerability demonstrates the importance of implementing defense-in-depth strategies, as the absence of CSRF protection in one component of a larger system creates a critical weakness that can be exploited to compromise the entire network infrastructure. Regular security assessments and penetration testing should be conducted to identify similar weaknesses in other network services and applications that may be vulnerable to similar CSRF attacks.