CVE-2018-25115 in DIR-110
Summary
by MITRE • 08/28/2025
Multiple D-Link DIR-series routers, including DIR-110, DIR-412, DIR-600, DIR-610, DIR-615, DIR-645, and DIR-815 firmware version 1.03, contain a vulnerability in the service.cgi endpoint that allows remote attackers to execute arbitrary system commands without authentication. The flaw stems from improper input handling in the EVENT=CHECKFW parameter, which is passed directly to the system shell without sanitization. A crafted HTTP POST request can inject commands that are executed with root privileges, resulting in full device compromise. These router models are no longer supported at the time of assignment and affected version ranges may vary.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability identified as CVE-2018-25115 affects multiple D-Link DIR-series routers including models DIR-110, DIR-412, DIR-600, DIR-610, DIR-615, DIR-645, and DIR-815. This represents a critical remote code execution flaw that exists within the service.cgi endpoint of these networking devices. The vulnerability stems from insufficient input validation mechanisms within the EVENT=CHECKFW parameter processing, creating a pathway for malicious actors to inject arbitrary commands directly into the system shell. The affected firmware version 1.03 demonstrates a fundamental failure in secure coding practices where user-supplied input is not properly sanitized or validated before being passed to system-level functions. This vulnerability is particularly concerning as it operates without requiring any authentication credentials, making it accessible to any remote attacker who can reach the device's network interface.
The technical implementation of this vulnerability involves a classic command injection flaw that aligns with CWE-77 and CWE-89 categories, where untrusted data is directly incorporated into shell commands without proper sanitization. When a malicious HTTP POST request is crafted with specifically formatted EVENT=CHECKFW parameters, the router's web server processes this input without adequate validation, directly executing the injected commands within the system shell context. The commands execute with root privileges, providing attackers with complete administrative control over the affected devices. This privilege escalation occurs because the vulnerable component operates with elevated permissions, and the lack of input sanitization allows attackers to bypass normal access controls. The vulnerability's exploitation requires only basic network connectivity to the device and knowledge of the service.cgi endpoint, making it particularly dangerous for widely deployed networking equipment.
The operational impact of this vulnerability extends beyond simple device compromise to potentially enable broader network infiltration and attack propagation. Once an attacker gains root access to a compromised router, they can manipulate network traffic, redirect DNS requests, install persistent backdoors, or use the device as a pivot point for attacking other systems within the local network. The affected devices being part of the DIR-series family indicates a widespread deployment across both residential and small business environments, where these routers often serve as the primary gateway to the internet. This vulnerability creates a significant risk for organizations relying on D-Link equipment, as the compromised devices can be used to conduct man-in-the-middle attacks, data exfiltration, or to establish persistent access points within networks. The lack of authentication requirements means that attackers do not need to guess passwords or exploit additional vulnerabilities to gain initial access.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates from D-Link if available, though the affected models are noted as no longer supported, limiting official patch availability. Network administrators should implement firewall rules to restrict access to the service.cgi endpoint and other potentially vulnerable web interfaces, particularly when these devices are exposed to the internet. The use of network segmentation and monitoring can help detect anomalous traffic patterns that may indicate exploitation attempts. Additionally, organizations should consider implementing intrusion detection systems that can identify suspicious HTTP POST requests containing command injection patterns. The vulnerability serves as a reminder of the importance of secure coding practices and input validation in embedded systems, particularly those with web interfaces that handle user input. Organizations should conduct comprehensive inventory assessments to identify all affected devices and implement alternative security measures such as network access control lists or dedicated network appliances to protect against similar vulnerabilities in legacy equipment. The incident highlights the critical need for ongoing security assessments of deployed network infrastructure, particularly for devices that are no longer receiving vendor support or security updates.