CVE-2016-10106 in FVS336Gv3
Summary
by MITRE
Directory traversal vulnerability in scgi-bin/platform.cgi on NETGEAR FVS336Gv3, FVS318N, FVS318Gv2, and SRX5308 devices with firmware before 4.3.3-8 allows remote authenticated users to read arbitrary files via a .. (dot dot) in the thispage parameter, as demonstrated by reading the /etc/shadow file.
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Analysis
by VulDB Data Team • 02/06/2020
This vulnerability represents a critical directory traversal flaw in NETGEAR's network security appliances, specifically affecting models including the FVS336Gv3, FVS318N, FVS318Gv2, and SRX5308 devices. The issue resides within the scgi-bin/platform.cgi component of the web interface, where the application fails to properly validate user input before processing file requests. The vulnerability stems from insufficient sanitization of the thispage parameter, allowing attackers to manipulate directory navigation sequences using standard dot-dot-slash notation. This weakness enables remote authenticated users to bypass normal access controls and retrieve arbitrary files from the device's file system, with the attack vector demonstrated through access to sensitive system files such as /etc/shadow. The vulnerability is classified under CWE-22 as a directory traversal attack, which represents a fundamental flaw in input validation and file access control mechanisms. The attack requires only authentication credentials, making it particularly dangerous as it can be exploited by insiders or compromised accounts. Network security devices are particularly vulnerable to such attacks due to their privileged access to system resources and the sensitive information they contain.
The technical exploitation of this vulnerability demonstrates a classic path traversal pattern where the attacker crafts a malicious request containing directory traversal sequences that allow navigation outside of the intended directory scope. The scgi-bin/platform.cgi script processes the thispage parameter without adequate validation, permitting attackers to specify file paths that include ../ sequences to move up directory levels. This allows access to sensitive system files including configuration data, authentication information, and system binaries that should remain protected from unauthorized access. The impact is particularly severe because the /etc/shadow file contains hashed passwords for system users, which if compromised could lead to complete system compromise. The vulnerability affects firmware versions prior to 4.3.3-8, indicating that NETGEAR had not yet implemented proper input validation mechanisms to prevent such attacks. The attack surface is further expanded by the fact that these devices are typically deployed in network security roles where they handle sensitive network traffic and contain critical infrastructure information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the ability to extract sensitive configuration data and authentication credentials that could be used for further attacks within the network. Compromised devices could serve as entry points for lateral movement attacks, allowing attackers to pivot from the compromised router to other network segments. The vulnerability also exposes the underlying system architecture and configuration details, which could aid in planning more sophisticated attacks against the network infrastructure. Organizations using these affected devices face significant risk of unauthorized access to their network security controls, potentially leading to complete network compromise. The attack vector is particularly concerning because it requires only authenticated access, meaning that a compromised user account or insider threat could exploit this vulnerability. According to ATT&CK framework, this vulnerability maps to T1078 Valid Accounts and T1566 Phishing, as it leverages legitimate authentication mechanisms to gain unauthorized access to sensitive system information. The vulnerability also represents a failure in the principle of least privilege, as the web interface should not permit arbitrary file access through parameter manipulation.
Mitigation strategies for this vulnerability require immediate firmware updates to versions 4.3.3-8 or later, which contain proper input validation and sanitization mechanisms to prevent directory traversal attacks. Network administrators should implement strict access controls and monitor for unauthorized access attempts to network security devices. Regular security audits should be conducted to identify and remediate similar vulnerabilities in other network infrastructure components. The implementation of web application firewalls and input validation rules can provide additional protection layers against similar attacks. Organizations should also consider segmenting network security devices and implementing network monitoring to detect anomalous access patterns that might indicate exploitation attempts. Security awareness training for network administrators is crucial to prevent unauthorized access through compromised credentials. The vulnerability highlights the importance of secure coding practices and input validation in network security appliances, particularly in components that handle user input and file system operations. Regular vulnerability assessments and penetration testing should be performed to identify similar weaknesses in other network infrastructure devices. Additionally, implementing network segmentation and access controls can limit the potential impact of such vulnerabilities by reducing the attack surface and preventing lateral movement within the network.