CVE-2017-14420 in DIR-850L
Summary
by MITRE
The D-Link NPAPI extension, as used on D-Link DIR-850L REV. A (with firmware through FW114WWb07_h2ab_beta1) and REV. B (with firmware through FW208WWb02) devices, does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.
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Analysis
by VulDB Data Team • 11/15/2019
The vulnerability identified as CVE-2017-14420 affects the D-Link DIR-850L router series, specifically impacting devices with firmware versions through FW114WWb07_h2ab_beta1 for revision A and FW208WWb02 for revision B. This security flaw resides within the D-Link NPAPI extension component that handles secure communications between the router and remote servers. The issue represents a critical failure in the certificate validation process, where the router fails to properly verify X.509 certificates presented by SSL servers during secure connections.
The technical flaw manifests as a complete absence of certificate verification mechanisms within the NPAPI extension implementation. This cryptographic weakness allows attackers to perform man-in-the-middle attacks by presenting forged SSL certificates that appear legitimate to the vulnerable router. The vulnerability directly maps to CWE-295, which describes improper certificate validation, and specifically addresses the failure to validate certificate authority signatures and certificate chains. The router's inability to verify certificate authenticity creates a trust relationship that can be easily exploited by malicious actors.
Operationally, this vulnerability exposes users to significant risks including data interception, credential theft, and unauthorized access to sensitive information transmitted through the router's secure channels. Attackers can exploit this weakness to eavesdrop on communications, inject malicious content, or redirect traffic to malicious servers without detection. The impact extends beyond simple data theft as it compromises the entire secure communication infrastructure of the device, potentially allowing attackers to escalate privileges or gain persistent access to the network. This vulnerability particularly affects enterprise and home users who rely on the router's secure communication capabilities for web browsing, email, and other sensitive online activities.
Mitigation strategies for CVE-2017-14420 should prioritize immediate firmware updates from D-Link to address the certificate validation flaw. Network administrators should implement additional monitoring measures to detect unusual traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper certificate validation in secure communications and aligns with ATT&CK technique T1041, which covers data compression and encryption for data exfiltration. Organizations should also consider implementing network segmentation and additional security controls to limit the potential impact of such certificate validation failures. Regular security assessments of network devices and prompt patch management remain essential practices to prevent exploitation of similar cryptographic weaknesses in other network infrastructure components.