CVE-2019-18666 in DAP-1360
Summary
by MITRE
An issue was discovered on D-Link DAP-1360 revision F devices. Remote attackers can start a telnet service without authorization via an undocumented HTTP request. Although this is the primary vulnerability, the impact depends on the firmware version. Versions 609EU through 613EUbeta were tested. Versions through 6.12b01 have weak root credentials, allowing an attacker to gain remote root access. After 6.12b01, the root credentials were changed but the telnet service can still be started without authorization.
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Analysis
by VulDB Data Team • 05/16/2020
The vulnerability identified as CVE-2019-18666 affects D-Link DAP-1360 wireless access point devices operating on revision F firmware. This represents a critical security flaw that allows remote attackers to gain unauthorized access to network devices through an undocumented HTTP request mechanism. The vulnerability specifically enables unauthorized telnet service activation, which fundamentally undermines the device's security posture and creates multiple attack vectors for malicious actors. The issue is particularly concerning because it operates outside the normal authentication mechanisms and exploits undocumented functionality within the device's web interface.
The technical flaw manifests through an undocumented HTTP request that, when properly crafted, can initiate the telnet service on the affected D-Link device. This vulnerability falls under CWE-668, which describes "Exposure of Resource to Wrong Sphere" where an attacker can gain access to resources that should be restricted. The exploitation process involves sending a specific HTTP request that triggers the device to start the telnet daemon without requiring any authentication credentials. This behavior creates a backdoor mechanism that bypasses normal security controls and allows for remote command execution capabilities. The vulnerability is particularly dangerous because it leverages an undocumented interface that security professionals and device administrators would not typically expect to be accessible.
The operational impact of this vulnerability varies significantly based on the firmware version installed on the device. Testing confirmed the issue affects firmware versions 609EU through 613EUbeta, with the most critical exposure occurring in versions through 6.12b01 where weak root credentials are present. This means that attackers could potentially gain full root access to the device through a combination of the unauthorized telnet service activation and default weak credentials. The vulnerability creates a multi-layered attack surface where even if one vector is patched, the other remains exploitable. Devices running firmware versions after 6.12b01 are still at risk because while the root credentials were changed, the telnet service can still be started without authorization, maintaining the core vulnerability.
The security implications extend beyond simple unauthorized access to include potential network compromise and lateral movement capabilities. Once an attacker gains access through this vulnerability, they can establish persistent access to the network infrastructure and potentially use the device as a pivot point for attacking other network segments. This vulnerability aligns with ATT&CK technique T1075 which describes "Pass the Hash" and T1021.001 which covers "Remote Services: Remote Desktop Protocol" in the context of unauthorized network access. The device's telnet service activation creates a persistent threat vector that can be exploited for extended periods without detection, making it particularly dangerous for enterprise environments where network security is paramount.
Mitigation strategies should focus on immediate firmware updates to the latest available versions that address both the unauthorized telnet service activation and any credential weaknesses. Network administrators should implement network segmentation and monitoring to detect unauthorized telnet service activity on their networks. The vulnerability highlights the importance of proper input validation and access control mechanisms, as well as the need for thorough security testing of all device interfaces. Organizations should also consider implementing network access controls and firewall rules that restrict access to telnet and SSH services to only authorized network segments. Regular security assessments of network infrastructure should include verification of device configurations and monitoring for unauthorized service activation to prevent exploitation of similar vulnerabilities.