CVE-2017-14427 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/run/storage_account_root permissions.
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Analysis
by VulDB Data Team • 11/15/2019
The vulnerability identified as CVE-2017-14427 affects D-Link DIR-850L wireless routers across multiple firmware versions, specifically targeting the storage_account_root file permissions within the device's file system. This issue represents a critical misconfiguration that exposes sensitive system information and creates potential attack vectors for malicious actors. The affected devices operate with overly permissive file permissions set to 0666, which grants read and write access to all users including unprivileged accounts. This misconfiguration allows unauthorized access to storage account information that should remain protected within the router's secure environment.
The technical flaw stems from improper file system permission management within the D-Link router firmware implementation. The 0666 permission setting creates a world-writable and world-readable file system entry at /var/run/storage_account_root, which typically contains user credentials, storage configurations, or other sensitive account-related data. This permission structure violates fundamental security principles of least privilege and mandatory access controls, as it allows any process or user account on the device to modify or extract sensitive information from this critical storage location. The vulnerability is particularly concerning because it affects both revision A and B models, indicating a widespread firmware issue that impacts a significant number of deployed devices.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates opportunities for privilege escalation and persistent access to the affected network devices. Attackers can leverage this misconfiguration to gain unauthorized access to storage account information, potentially enabling them to compromise additional network resources or establish persistent backdoors within the router's operational environment. The exposure of storage account root permissions represents a failure in the principle of least privilege, allowing any user account to modify critical system files that should only be accessible to system administrators or specific privileged processes. This vulnerability can be exploited by attackers who have gained initial access to the device through other means, or potentially through network-based attacks that target the router's web interface or management services.
Mitigation strategies for this vulnerability should focus on immediate permission correction and firmware updates to address the underlying configuration issue. System administrators should verify and correct file permissions on affected devices, ensuring that sensitive system files are protected with appropriate access controls such as 0600 or 0640 permissions. The most effective long-term solution involves updating the firmware to versions that properly implement secure file permissions and address the root cause of the misconfiguration. Organizations should also implement network monitoring to detect unauthorized access attempts to router management interfaces and consider network segmentation to limit exposure of these devices to untrusted network segments. This vulnerability aligns with CWE-732: Incorrect Permission Assignment for Critical Resource, which emphasizes the importance of proper access control mechanisms. From an attack perspective, this misconfiguration could enable techniques categorized under ATT&CK tactic TA0006: Credential Access, specifically targeting credential dumping and privilege escalation methods that exploit weak file system permissions.