CVE-2017-13087 in WPA2
Summary
by MITRE
Wi-Fi Protected Access (WPA and WPA2) that support 802.11v allows reinstallation of the Group Temporal Key (GTK) when processing a Wireless Network Management (WNM) Sleep Mode Response frame, allowing an attacker within radio range to replay frames from access points to clients.
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Analysis
by VulDB Data Team • 01/03/2023
The vulnerability described in CVE-2017-13087 represents a critical flaw in the Wi-Fi Protected Access protocol family, specifically affecting both WPA and WPA2 implementations that support the 802.11v standard. This weakness resides in the cryptographic key management mechanism of wireless networks, where the Group Temporal Key (GTK) can be incorrectly reinstalled during the processing of Wireless Network Management (WNM) Sleep Mode Response frames. The flaw operates at the intersection of wireless network security protocols and wireless network management standards, creating a scenario where legitimate network traffic can be exploited by malicious actors within radio range.
The technical implementation of this vulnerability stems from improper handling of GTK reinstallation within the 802.11v wireless management framework. When a wireless client receives a WNM Sleep Mode Response frame from an access point, the client's wireless driver processes this frame and may inadvertently reinstall an already established GTK. This occurs due to insufficient validation of the frame's cryptographic state and lack of proper key state tracking during the sleep mode transition process. The vulnerability specifically affects the Group Temporal Key management, which is responsible for encrypting multicast and broadcast traffic within a wireless network, making it particularly dangerous as it compromises the confidentiality of traffic intended for multiple recipients.
The operational impact of this vulnerability extends beyond simple data interception, as it enables an attacker to perform cryptographic replay attacks against wireless clients. An attacker within radio range can capture legitimate WNM Sleep Mode Response frames and replay them to a client device, causing the client to reinstall an existing GTK. This reinstallation allows the attacker to decrypt previously captured multicast and broadcast traffic, potentially gaining access to sensitive information transmitted within the wireless network. The vulnerability is particularly concerning because it can be exploited without requiring authentication or advanced privileges, making it accessible to any attacker with physical proximity to the wireless network.
This vulnerability aligns with CWE-327, which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions, and specifically relates to improper key management practices. The attack vector maps to ATT&CK technique T1486, which covers data encryption for ransom, though in this case the encryption is not for ransom but for unauthorized access to network traffic. The vulnerability also connects to T1046, network service scanning, as attackers may need to identify vulnerable wireless clients within range. Security professionals should note that this flaw demonstrates the complexity of wireless security protocols and highlights the importance of proper key state management in cryptographic implementations.
Mitigation strategies for CVE-2017-13087 require both immediate patching and network configuration adjustments. Network administrators should ensure all wireless access points and client devices are updated with firmware and driver patches that address the GTK reinstallation issue. The most effective immediate solution involves implementing proper key rotation mechanisms and ensuring that wireless drivers correctly validate frame states before accepting GTK reinstallation requests. Network segmentation and monitoring solutions should be deployed to detect anomalous WNM frame patterns that may indicate exploitation attempts. Additionally, organizations should consider implementing network access control measures that limit wireless client connectivity and reduce the attack surface. The vulnerability underscores the importance of regular security assessments of wireless infrastructure and the need for comprehensive wireless security policies that address both management and data plane vulnerabilities.