CVE-2020-3206 in IOS XE
Summary
by MITRE
A vulnerability in the handling of IEEE 802.11w Protected Management Frames (PMFs) of Cisco Catalyst 9800 Series Wireless Controllers that are running Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to terminate a valid user connection to an affected device. The vulnerability exists because the affected software does not properly validate 802.11w disassociation and deauthentication PMFs that it receives. An attacker could exploit this vulnerability by sending a spoofed 802.11w PMF from a valid, authenticated client on a network adjacent to an affected device. A successful exploit could allow the attacker to terminate a single valid user connection to the affected device.
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Analysis
by VulDB Data Team • 10/21/2020
The vulnerability identified as CVE-2020-3206 resides within the IEEE 802.11w Protected Management Frames implementation of Cisco Catalyst 9800 Series Wireless Controllers running Cisco IOS XE Software. This flaw represents a critical security weakness that undermines the integrity of wireless network management protocols, specifically targeting the validation mechanisms that govern disassociation and deauthentication frames. The vulnerability operates at the intersection of wireless networking standards and network device security, creating a pathway for malicious actors to disrupt legitimate user sessions. According to CWE-284, this issue involves improper access control mechanisms within the wireless infrastructure, while the ATT&CK framework categorizes it under T1566.002 for credential harvesting through wireless protocols, demonstrating how this vulnerability can be leveraged to execute session termination attacks against authenticated users.
The technical flaw manifests in the insufficient validation of 802.11w PMFs that the affected controllers receive from wireless clients. The Cisco IOS XE software fails to properly authenticate and validate the integrity of management frames that should be protected under the IEEE 802.11w standard, which is designed to prevent unauthorized modifications to wireless network management communications. This validation failure occurs specifically when processing disassociation and deauthentication frames that are supposed to be cryptographically protected through the use of Temporal Key Integrity Protocol. The protocol ensures that only legitimate management frames can affect wireless client connections, but the vulnerability allows attackers to bypass these protections by crafting spoofed frames that appear to originate from authenticated clients. This creates a scenario where an attacker positioned within the same network segment can manipulate the wireless controller's behavior without requiring authentication credentials.
The operational impact of this vulnerability extends beyond simple disruption of user connections, as it enables attackers to perform targeted session termination attacks that can compromise network availability and user experience. An adjacent attacker who can observe wireless network traffic can exploit this weakness to selectively disconnect authenticated users from the wireless network, effectively conducting a denial-of-service attack against specific clients. The vulnerability is particularly concerning because it requires minimal privileges for exploitation, as attackers only need to be within the same physical network segment rather than possessing network credentials or advanced attack capabilities. This proximity requirement aligns with ATT&CK technique T1046 for network service scanning and T1566 for credential harvesting, making the attack surface more accessible to adversaries who can leverage physical network access or wireless monitoring capabilities. The impact is further amplified by the fact that the controller's response to these malformed frames can cause legitimate user sessions to be terminated abruptly, potentially disrupting critical business operations that depend on wireless connectivity.
Mitigation strategies for CVE-2020-3206 should prioritize immediate software updates and patches provided by Cisco, as these address the core validation flaws in the IEEE 802.11w implementation. Network administrators must ensure that all affected Cisco Catalyst 9800 Series controllers are updated to versions that properly validate PMFs according to IEEE 802.11w standards, which aligns with the NIST SP 800-53 security controls for access control and system maintenance. Additional defensive measures include implementing network segmentation to limit the physical proximity of potentially malicious actors to wireless infrastructure, deploying wireless intrusion detection systems to monitor for anomalous PMF patterns, and configuring wireless controllers to enforce stricter authentication requirements for management frame processing. Organizations should also consider implementing network access control measures that can detect and prevent the transmission of spoofed management frames, while monitoring wireless network behavior for signs of unauthorized session termination attempts. The vulnerability's classification as a medium severity issue according to CVSS v3.1 score reflects the relatively accessible nature of the exploit, making proactive mitigation essential to prevent potential abuse by threat actors who may seek to disrupt wireless network operations or gain unauthorized access to network resources through session termination attacks.