CVE-2018-0412 in Small Business 100 Series Wireless Access Point
Summary
by MITRE
A vulnerability in the implementation of Extensible Authentication Protocol over LAN (EAPOL) functionality in Cisco Small Business 100 Series Wireless Access Points and Cisco Small Business 300 Series Wireless Access Points could allow an unauthenticated, adjacent attacker to force the downgrade of the encryption algorithm that is used between an authenticator (access point) and a supplicant (Wi-Fi client). The vulnerability is due to the improper processing of certain EAPOL messages that are received during the Wi-Fi handshake process. An attacker could exploit this vulnerability by establishing a man-in-the-middle position between a supplicant and an authenticator and manipulating an EAPOL message exchange to force usage of a WPA-TKIP cipher instead of the more secure AES-CCMP cipher. A successful exploit could allow the attacker to conduct subsequent cryptographic attacks, which could lead to the disclosure of confidential information. Cisco Bug IDs: CSCvj29229.
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Analysis
by VulDB Data Team • 03/16/2020
The vulnerability described in CVE-2018-0412 represents a critical weakness in the wireless authentication mechanisms of Cisco Small Business series wireless access points. This flaw specifically affects the Extensible Authentication Protocol over LAN (EAPOL) implementation within Cisco Small Business 100 Series and 300 Series Wireless Access Points, creating a pathway for adjacent attackers to manipulate the encryption negotiation process during Wi-Fi handshakes. The vulnerability stems from improper handling of EAPOL messages during the authentication phase, which allows an attacker to intercept and modify communication between wireless clients and access points. This weakness fundamentally compromises the security posture of wireless networks by enabling downgrade attacks that force the use of less secure encryption algorithms.
The technical exploitation of this vulnerability requires an attacker to be physically adjacent to the target wireless network, positioning them within the same broadcast domain as the wireless clients and access points. During the standard EAPOL handshake process, the attacker can manipulate specific EAPOL message exchanges to force the authentication system to negotiate and utilize the WPA-TKIP cipher instead of the more robust AES-CCMP cipher. This downgrade attack specifically targets the encryption algorithm negotiation phase, where the system should automatically select the strongest available cipher suite. The vulnerability is classified under CWE-310 as a weakness related to cryptographic implementation, specifically involving improper handling of cryptographic protocols during authentication. The attack vector aligns with ATT&CK technique T1046 which describes the use of network service scanning to identify potential attack targets, and T1075 which covers the use of legitimate credentials to access systems.
The operational impact of this vulnerability extends beyond simple encryption downgrade, as it creates opportunities for more sophisticated cryptographic attacks that can lead to complete network compromise. When WPA-TKIP encryption is forced, the system becomes vulnerable to known weaknesses in the TKIP protocol, including the ability to capture and replay authentication frames to obtain session keys. This weakness allows attackers to potentially decrypt wireless traffic, monitor network communications, and even inject malicious data into the network. The vulnerability is particularly concerning for small business environments where wireless networks often handle sensitive corporate data, financial transactions, and personal information. The attack requires minimal sophistication and can be executed by an attacker with basic wireless networking knowledge and adjacent access to the target network.
Mitigation strategies for CVE-2018-0412 should focus on both immediate remediation and long-term security improvements. Cisco has released patches and software updates specifically addressing this vulnerability, which should be deployed immediately across all affected access point models. Network administrators should also implement additional security controls such as disabling WPA-TKIP encryption entirely and enforcing the use of AES-CCMP cipher suites. The implementation of 802.1X authentication with strong certificate-based authentication can provide additional layers of protection against such downgrade attacks. Organizations should also consider network segmentation strategies to limit the impact of potential wireless compromises and implement monitoring solutions to detect unusual EAPOL message patterns that might indicate active exploitation attempts. From an ATT&CK perspective, implementing network detection and response capabilities aligned with T1041 and T1071 can help identify and block malicious EAPOL message manipulation attempts. The vulnerability demonstrates the importance of proper cryptographic protocol implementation and the necessity of maintaining up-to-date firmware across all network infrastructure components to prevent exploitation of known weaknesses in authentication mechanisms.