CVE-2017-7851 in DCS-936L
Summary
by MITRE
D-Link DCS-936L devices with firmware before 1.05.07 have an inadequate CSRF protection mechanism that requires the device's IP address to be a substring of the HTTP Referer header.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability identified as CVE-2017-7851 affects D-Link DCS-936L network cameras running firmware versions prior to 1.05.07, representing a significant security weakness in the device's cross-site request forgery protection mechanisms. This flaw stems from the device's reliance on the HTTP Referer header as a validation mechanism, which creates a dangerous dependency on client-side information that can be easily manipulated or bypassed by attackers. The specific implementation requires that the device's IP address must appear as a substring within the Referer header, a validation approach that fundamentally undermines the security model and exposes the device to unauthorized administrative actions.
The technical implementation of this vulnerability demonstrates a critical failure in the device's authentication and authorization framework, where the system assumes that the Referer header contains reliable information about the originating request source. This approach violates fundamental security principles and represents a classic example of trusting client-side data for security decisions. The vulnerability allows an attacker to construct malicious web pages that, when visited by an authenticated user, can trigger administrative actions on the camera without proper authorization. This occurs because the device's CSRF protection mechanism is insufficiently robust and relies on a single, easily manipulable HTTP header field that can be spoofed or omitted entirely.
From an operational perspective, this vulnerability creates a severe risk for users of these network cameras, as it enables attackers to perform unauthorized configuration changes, modify camera settings, or potentially gain complete administrative control over the device. The impact extends beyond simple configuration changes since these cameras are often used in security-critical environments where unauthorized access could lead to complete surveillance system compromise. The vulnerability is particularly concerning because it affects devices that may be deployed in sensitive locations such as corporate offices, retail environments, or residential properties where the integrity of the surveillance system is paramount for security operations.
The security implications of this vulnerability align with CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses in software applications. This classification indicates that the device lacks proper anti-CSRF token mechanisms and instead relies on flawed validation logic that can be easily circumvented. The attack vector described in the vulnerability corresponds to techniques outlined in the ATT&CK framework under the T1212 - Exploitation for Credential Access and T1071.004 - Application Layer Protocol: DNS categories, as attackers can leverage this weakness to manipulate network device configurations. Organizations using these devices should consider implementing network segmentation, regular firmware updates, and monitoring for suspicious administrative activities as part of their mitigation strategies.
The root cause of this vulnerability demonstrates a fundamental misunderstanding of how CSRF protection should be implemented in network devices, where the security model fails to account for the inherent weaknesses of HTTP header-based validation. This weakness represents a classic case of insufficient input validation and inadequate security controls that can be exploited through simple web-based attacks. The vulnerability's impact is amplified by the fact that many users may not be aware of the security implications of their network camera configurations, particularly when these devices are deployed in environments where they are not regularly monitored or updated. The lack of proper CSRF token generation and validation mechanisms leaves the device completely exposed to automated exploitation attempts and highlights the importance of implementing robust security controls in embedded network devices.
Organizations should prioritize updating their D-Link DCS-936L devices to firmware version 1.05.07 or later, which addresses this specific CSRF protection weakness. Additionally, network administrators should implement monitoring solutions that can detect unusual administrative activities on network cameras and ensure that these devices are properly secured within network infrastructure. The vulnerability serves as a reminder of the critical importance of proper CSRF protection mechanisms in network devices and the potential consequences of relying on weak validation approaches that can be easily bypassed by determined attackers.