Protected Management Frames (Management Frame Protection)
By default, 802.11 management frames are unauthenticated and hence not protected against spoofing. Infrastructure management frame protection (MFP) and 802.11w protected management frames (PMF) provide protection against such attacks.
Infrastructure MFP protects management frames by detecting adversaries that are invoking denial-of-service attacks, flooding the network with associations and probes, interjecting as rogue APs, and affecting network performance by attacking the QoS and radio measurement frames. Infrastructure MFP is a global setting that provides a quick and effective means to detect and report phishing incidents.
Specifically, infrastructure MFP protects 802.11 session management functions by adding message integrity check information elements (MIC IEs) to the management frames emitted by APs (and not those emitted by clients), which are then validated by other APs in the network. Infrastructure MFP is passive, can detect and report intrusions but has no means to stop them.
Infrastructure MFP consists of three main components:
Management frame protection: The AP protects the management frames it transmits by adding a MIC IE to each frame. Any attempt to copy, alter, or replay the frame invalidates the MIC, causing any receiving AP configured to detect MFP frames to report the discrepancy. MFP is supported for use with Cisco Aironet lightweight APs.
Management frame validation: In infrastructure MFP, the AP validates every management frame that it receives from other APs in the network. It ensures that the MIC IE is present (when the originator is configured to transmit MFP frames) and matches the content of the management frame. If it receives any frame that does not contain a valid MIC IE from a BSSID belonging to an AP that is configured to transmit MFP frames, it reports the discrepancy to the network management system. In order for the timestamps to operate properly, all controllers must be Network Time Protocol (NTP) synchronized.
Event reporting: The AP notifies the controller when it detects an anomaly, and the controller aggregates the received anomaly events and can report the results through SNMP traps to the network management system.
Infrastructure MFP is disabled by default, and you can enable it globally. When you upgrade from a previous software release, infrastructure MFP is disabled globally if you have enabled AP authentication because the two features are mutually exclusive. When you enable infrastructure MFP globally, signature generation (adding MICs to outbound frames) can be disabled for selected WLANs, and validation can be disabled for selected APs.
CCXv5 client MFP is no longer supported. Client MFP is enabled as optional by default on WLANs that are configured for WPA2. However, client MFP is not supported on Wave 2 APs or 802.11ax Wi-Fi6 APs, and there exist no clients that support CCXv5.
802.11w standard protects the transmission of control and management frames, between APs and clients, against forgery and replay attacks. The frame types protected include Disassociation, Deauthentication, and Robust Action frames such as:
Quality of Service (QoS)
Fast Basic Service Set (BSS) Transition
For information about 802.11w PMF, see the 802.11w section.
Additional Reference: Configure 802.11w Management Frame Protection on WLC
This section contains the following subsections: