Privilege Escalation in D-Link DIR-1253 via Shadow File

Executive Summary

CVE-2026-52533 is a vulnerability in the D-Link DIR-1253 router, specifically version 1.0.1.250923.142435. The issue allows an attacker to escalate privileges on the affected device by exploiting the etc/shadow component file. This file typically stores password hashes for user accounts on Unix-like systems, and unauthorized access or manipulation of this file can grant an attacker elevated privileges.

The vulnerability is classified with a CVSS v3.1 base score of 9.8, indicating a critical severity. The vector AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H means the attack can be executed remotely over a network with low complexity, no privileges or user interaction required, and can result in high impacts to confidentiality, integrity, and availability of the system.

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Detection Guidance

Detecting this vulnerability on your network or system involves checking for the presence of the vulnerable D-Link DIR-1253 firmware version (v.1.0.1.250923.142435) and verifying if the etc/shadow component file is accessible or misconfigured.

• Identify D-Link DIR-1253 devices on your network using network scanning tools like Nmap. Example command: nmap -p 80,443 --open -sV <network_range> | grep 'D-Link DIR-1253'.
• Check the firmware version of the D-Link DIR-1253 device by accessing its web interface or using command-line tools if SSH access is available. Look for version v.1.0.1.250923.142435.
• Verify if the etc/shadow file is improperly exposed or accessible. This may require authenticated access to the device. Example command (if SSH is enabled): cat /etc/shadow.

If the etc/shadow file is accessible without proper authorization, the device is likely vulnerable.

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Impact Analysis

If you are using the D-Link DIR-1253 router with the affected firmware version (1.0.1.250923.142435), this vulnerability could have severe consequences for you.

• An attacker could gain unauthorized administrative access to your router, allowing them to modify settings, intercept network traffic, or launch further attacks on devices connected to your network.
• The attacker could extract sensitive information, such as stored credentials or personal data, from the router or connected devices.
• The attacker could disrupt network operations, leading to downtime or denial of service for connected devices.
• Since the vulnerability can be exploited remotely, the attacker does not need physical access to your router or network.

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Compliance Impact

This vulnerability could have significant implications for compliance with various standards and regulations, depending on how the affected router is used in your environment.

• GDPR (General Data Protection Regulation): If the router is used in an environment where personal data of EU citizens is processed or stored, a breach resulting from this vulnerability could lead to unauthorized access to that data. This may constitute a reportable data breach under GDPR, potentially resulting in fines and reputational damage.
• HIPAA (Health Insurance Portability and Accountability Act): If the router is part of a healthcare organization's network handling protected health information (PHI), exploitation of this vulnerability could lead to unauthorized access to PHI. This would be a violation of HIPAA's Security Rule, potentially resulting in penalties and mandatory corrective actions.
• Other standards like PCI DSS (Payment Card Industry Data Security Standard): If the router is involved in processing, transmitting, or storing payment card data, this vulnerability could lead to non-compliance with PCI DSS requirements, as it may allow unauthorized access to cardholder data.

In general, the vulnerability undermines the security controls required by these regulations, as it allows unauthorized access and control over a critical network device. Organizations must ensure that such vulnerabilities are patched or mitigated to maintain compliance.

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Mitigation Strategies

To mitigate this vulnerability, follow these immediate steps:

• Disconnect the affected D-Link DIR-1253 device from the network to prevent potential exploitation.
• Check the D-Link official website or support portal for firmware updates that address this vulnerability. Apply the latest firmware update if available.
• If no patch is available, consider replacing the device with a supported model or one that receives security updates.
• Restrict network access to the device by implementing firewall rules or segmenting the network to limit exposure.
• Monitor the device for unusual activity or unauthorized access attempts.
• Change default credentials and ensure strong, unique passwords are used for all accounts on the device.
• Disable unnecessary services or features that may increase the attack surface, such as remote administration if not required.

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