CVE-2018-18907 in DIR-850L
Summary
by MITRE • 06/17/2022
An issue was discovered on D-Link DIR-850L 1.21WW devices. A partially completed WPA handshake is sufficient for obtaining full access to the wireless network. A client can access the network by sending packets on Data Frames to the AP without encryption.
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Analysis
by VulDB Data Team • 06/17/2022
The vulnerability identified as CVE-2018-18907 affects D-Link DIR-850L 1.21WW wireless routers and represents a critical weakness in the wireless security implementation that fundamentally undermines the integrity of WPA encryption protocols. This flaw allows unauthorized network access through a sophisticated exploitation technique that leverages incomplete WPA handshakes to achieve full network compromise. The vulnerability specifically targets the authentication and key exchange mechanisms that are essential for securing wireless communications, creating a significant security gap that can be exploited by malicious actors without requiring advanced technical skills or specialized equipment.
The technical flaw manifests through the router's improper handling of WPA handshake completion processes, where the device fails to properly validate the authenticity of wireless clients attempting to connect to the network. This vulnerability stems from inadequate cryptographic validation procedures that permit incomplete handshake sequences to be accepted as valid authentication tokens. When a client device attempts to connect to the wireless network, the router should require a complete and verified WPA handshake process involving multiple message exchanges between the client and access point to establish secure encryption keys. However, the DIR-850L 1.21WW firmware fails to enforce proper handshake completion, allowing attackers to exploit this weakness by crafting specific data frames that bypass normal authentication procedures. The vulnerability essentially creates a backdoor mechanism where clients can establish network connectivity using only partial handshake information, effectively undermining the core security principles of wireless encryption protocols.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it provides attackers with complete network compromise capabilities that can be exploited for various malicious activities including man-in-the-middle attacks, data interception, and network reconnaissance. Once an attacker successfully exploits this vulnerability, they gain unrestricted access to all network resources and can potentially escalate their privileges to gain administrative control over the router itself. This creates a persistent threat vector that can be maintained indefinitely, as the vulnerability exists at the firmware level and can be exploited repeatedly without requiring additional authentication credentials. The implications are particularly severe for organizations relying on these devices for network security, as the vulnerability can be exploited from remote locations without physical access to the device, making it a particularly attractive target for cybercriminals seeking to establish persistent network footholds.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-310 Cryptographic Issues and aligns with multiple ATT&CK techniques including T1046 Network Service Scanning and T1071.1 Application Layer Protocol Web Protocols, as the exploitation involves manipulating network protocols to bypass security controls. The vulnerability also demonstrates characteristics consistent with T1566 Impairing Defenses, where the attacker can disable or bypass the router's wireless security mechanisms through protocol manipulation. Mitigation strategies should focus on immediate firmware updates from D-Link, network segmentation to limit the impact of potential compromises, and implementation of additional security controls such as network access control lists and intrusion detection systems. Organizations should also consider deploying wireless intrusion prevention systems to monitor for suspicious handshake patterns and unauthorized network access attempts. The vulnerability highlights the critical importance of proper cryptographic implementation and the need for comprehensive security testing of network infrastructure devices to prevent similar weaknesses from being exploited in production environments.