CVE-2011-5053 in Wifi Protected Setup Protocol
Summary
by MITRE
The Wi-Fi Protected Setup (WPS) protocol, when the "external registrar" authentication method is used, does not properly inform clients about failed PIN authentication, which makes it easier for remote attackers to discover the PIN value, and consequently discover the Wi-Fi network password or reconfigure an access point, by reading EAP-NACK messages.
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Analysis
by VulDB Data Team • 08/09/2024
The vulnerability described in CVE-2011-5053 resides within the Wi-Fi Protected Setup protocol, specifically when employing the external registrar authentication method. This flaw represents a significant security weakness in wireless network authentication mechanisms that has persisted for over a decade. The issue manifests when an attacker can observe and analyze the communication between a wireless access point and a client device during the WPS registration process, allowing for the exploitation of improper error handling within the protocol's authentication flow.
The technical flaw stems from the protocol's failure to adequately communicate authentication failures to client devices when using external registrar methods. During normal WPS operations, when a PIN authentication attempt fails, the system should properly inform the client of this failure through standardized error messages. However, in the affected implementations, these error notifications are either absent or insufficiently communicated, creating a scenario where attackers can systematically test PIN values while observing the network behavior. This miscommunication allows for the exploitation of a timing-based attack where the attacker can infer successful PIN guesses based on the lack of error responses from the access point.
The operational impact of this vulnerability extends beyond simple password discovery, as it enables attackers to potentially reconfigure access points entirely. When an attacker successfully determines the correct PIN through repeated guessing attempts, they gain the ability to modify network settings, change passwords, or even disable security features on the wireless access point. This represents a critical compromise of network security, as the WPS protocol was designed to provide a simplified method for connecting devices to secure networks, but in this case, it becomes a vector for network compromise. The vulnerability is particularly dangerous because it affects the fundamental authentication mechanism of WPS, which is widely deployed across consumer and enterprise wireless networks.
The attack vector for this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, specifically those related to credential access and privilege escalation. Attackers can leverage this weakness through passive network monitoring and active PIN brute-forcing techniques, making it a low-effort but high-impact attack method. The vulnerability also relates to CWE-284, which addresses improper access control in authentication systems, and CWE-312, which covers exposure of sensitive information through improper error handling. Organizations should implement mitigations including disabling WPS functionality entirely on wireless access points, as this addresses the root cause of the vulnerability. Additionally, network administrators should consider implementing stronger authentication methods and regularly auditing wireless network configurations to ensure that WPS is not inadvertently enabled in environments where it poses unnecessary risk. The vulnerability demonstrates the importance of proper error handling in security protocols and highlights how seemingly minor implementation flaws can create significant security risks in widely deployed systems.