CVE-2018-15516 in Central WiFiManager CWM-100
Summary
by MITRE
The FTP service on D-Link Central WiFiManager CWM-100 1.03 r0098 devices allows remote attackers to conduct a PORT command bounce scan via port 8000, resulting in SSRF.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability identified as CVE-2018-15516 affects the D-Link Central WiFiManager CWM-100 version 1.03 r0098 device, specifically targeting its FTP service implementation. This issue represents a significant security weakness that enables remote attackers to exploit the device's network configuration through a sophisticated attack vector involving port 8000 and the PORT command functionality. The device operates as a central WiFi management solution, making it a critical component in network infrastructure that requires robust security controls.
The technical flaw manifests through the improper handling of FTP PORT commands within the device's network service implementation. When an attacker sends a PORT command to the FTP service listening on port 8000, the device fails to properly validate or restrict the destination addresses that can be specified in the command. This misconfiguration allows for a port bounce scan technique where the attacker can use the device as an intermediary to probe internal network resources that would otherwise be inaccessible from external networks. The vulnerability essentially enables the device to act as a proxy for network reconnaissance activities, bypassing typical network segmentation controls.
This vulnerability creates a server-side request forgery (SSRF) condition that allows attackers to perform internal network scanning and potentially access sensitive internal services or resources. The attack leverages the device's legitimate FTP service functionality to create a tunnel for reconnaissance activities, making detection more challenging since the traffic appears to originate from a legitimate device within the network. The impact extends beyond simple scanning as it could potentially enable further exploitation of internal systems that are normally protected by network firewalls or other security controls.
The operational impact of this vulnerability is substantial for organizations relying on D-Link CWM-100 devices for WiFi management. Attackers can use this weakness to map internal network topologies, identify running services, and potentially discover additional vulnerabilities within the internal network. The attack requires no authentication and can be executed remotely, making it particularly dangerous for network administrators who may not be aware of the device's exposure. This vulnerability undermines the security posture of the entire network by providing an easy path for attackers to gain internal network intelligence.
Mitigation strategies should focus on immediate network segmentation and access control measures. Organizations should implement firewall rules to block external access to port 8000 on affected devices and consider disabling unnecessary FTP services when not required for legitimate operations. Network monitoring should be enhanced to detect anomalous FTP traffic patterns that may indicate exploitation attempts. Additionally, device firmware updates should be applied immediately when available from D-Link, though the vulnerability may require a complete firmware redesign to properly address the underlying protocol handling issues. This vulnerability aligns with CWE-918, which describes server-side request forgery, and represents a technique that could be categorized under ATT&CK technique T1046 for network service scanning. The flaw demonstrates how improper input validation in network services can create dangerous proxy capabilities that bypass traditional security controls.