Executive Summary

This vulnerability is an Absolute Path Traversal flaw in the D-Link DCS-850L device's Firmware Update Service, specifically in the 'uploadfirmware' function. It occurs because the service improperly handles the 'DownloadFile' argument, allowing an attacker on the local network to manipulate the file path using sequences like '../' to access files outside the intended directory. This means an attacker can read sensitive files on the device by tricking the firmware update process into opening arbitrary files. [1, 2]

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Impact Analysis

The vulnerability can compromise the confidentiality of the device by allowing unauthorized access to sensitive system files such as configuration files and password files. This unauthorized file access could facilitate further attacks or information disclosure. Since the affected product is no longer supported and no mitigations exist, the risk is heightened. Exploitation requires local network access, and a public proof-of-concept exploit is available, making it easier for attackers to exploit. [1, 2]

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Detection Guidance

Detection can focus on monitoring network traffic for attempts to exploit the path traversal in the Firmware Update Service's uploadfirmware function, specifically looking for HTTP requests containing path traversal sequences like "../" in the DownloadFile argument. Since the vulnerability requires local network access, inspecting local network traffic for suspicious firmware upload requests with unusual file paths is recommended. However, no specific detection commands or tools are provided in the available resources. [1, 2]

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Mitigation Strategies

Immediate mitigation steps include replacing the affected D-Link DCS-850L device with an alternative product, as the device is no longer supported by the vendor and no known countermeasures or patches exist. Additionally, restricting local network access to the device and monitoring for suspicious firmware upload activity may help reduce risk until replacement is possible. [1]

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Compliance Impact

This vulnerability compromises confidentiality by enabling unauthorized access to sensitive system files, which could lead to exposure of personal or protected data. Such unauthorized disclosure may result in non-compliance with data protection regulations like GDPR or HIPAA that require safeguarding sensitive information. Since the affected device is no longer supported and no mitigations are available, the risk to compliance is increased unless the device is replaced or properly secured. [1, 2]

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