CVE-2017-14424 in DIR-850L
Summary
by MITRE
D-Link DIR-850L REV. A (with firmware through FW114WWb07_h2ab_beta1) and REV. B (with firmware through FW208WWb02) devices have 0666 /var/passwd permissions.
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Analysis
by VulDB Data Team • 11/15/2019
The vulnerability identified as CVE-2017-14424 affects D-Link DIR-850L wireless routers across multiple firmware versions, specifically targeting devices with revision A running firmware through FW114WWb07_h2ab_beta1 and revision B running firmware through FW208WWb02. This security flaw represents a critical misconfiguration that exposes sensitive system files to unauthorized access, creating a significant attack surface for malicious actors. The vulnerability stems from improper file system permissions where the /var/passwd file is configured with overly permissive 0666 permissions, allowing any user or process to read, write, and execute operations on this critical system file.
The technical implementation of this vulnerability involves the improper configuration of file access controls within the router's embedded operating system. The /var/passwd file contains user account information and password hashes, making it a prime target for credential harvesting attacks. When a file is configured with 0666 permissions, it grants read and write access to all users including unprivileged accounts, which violates fundamental security principles of least privilege. This misconfiguration allows attackers to directly access and modify user authentication data, potentially enabling privilege escalation attacks and unauthorized system compromise. The vulnerability aligns with CWE-732, which describes inadequate permissions for critical resources, and represents a classic example of improper access control implementation.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential system compromise and unauthorized access to network resources. Attackers can exploit this flaw to extract user credentials and potentially gain administrative access to the router's management interface, which would provide complete control over network traffic, firewall rules, and device configuration settings. The exposure of /var/passwd permissions creates a persistent threat vector that remains active until the firmware is updated, allowing attackers to establish long-term access to the network infrastructure. This vulnerability is particularly concerning in enterprise environments where router security often serves as the first line of defense against internal network threats, and it aligns with attack patterns documented in the MITRE ATT&CK framework under privilege escalation and credential access techniques.
Mitigation strategies for this vulnerability should focus on immediate firmware updates from D-Link to address the underlying permission configuration issues. Network administrators should implement network segmentation and access controls to limit exposure of affected devices to critical network segments. Additionally, regular security audits should verify proper file system permissions across all network devices, with specific attention to system files containing authentication data. The vulnerability demonstrates the importance of proper security configuration management and highlights the need for regular security assessments of embedded network devices. Organizations should also implement monitoring solutions to detect unauthorized access attempts to critical system files and establish incident response procedures for addressing similar permission-related vulnerabilities. This case underscores the necessity of following security best practices for embedded systems and demonstrates how seemingly minor configuration errors can create significant security risks in network infrastructure devices.