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An Initial Security Analysis of the IEEE 802.1x Standard Tsai Hsien Pang 2004/11/4
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2004/11/42 Outline ► Introduction ► IEEE 802.1x Standard ► Man-in-Middle, Session Hijack attack ► Proposed solution ► Conclusion ► Reference
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2004/11/43 802.11 Security ► A wireless network is broadcast by nature, and the media is reachably-broadcast. ► Authentication and data encryption. ► The 802.11 standard for WLAN communications introduced the Wired Equivalent Privacy (WEP) protocol.
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2004/11/44 Basic Security Mechanisms ► Two Model: ad-hoc and infrastructure mode. ► A wireless client establish a relation with an AP, called an association. Unauthenticated and unassociated Authenticated and unassociated Authenticated and associated
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2004/11/45 802.11 State Machine ► STA and AP exchange authentication Management frames between state 1 and 2. ► Open system,share key and Mac-address based control list. ► WEP was designed to provide confidentiality.
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2004/11/46 WEP Protocol ► The WEP protocol is used in 802.11 networks to protect link level data during wireless transmission. ► It relies on a secret key k shared between the communicating parties to protected the body of a transmitted frame of data. ► Encryption of a frame proceeds: checksumming and encryption.
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2004/11/47 WEP Protocol (2)
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2004/11/48 The Drawback of WEP ► Keystream Reuse The IV field used by WEP is only 24 bits wide, nearly guaranteeing that the same IV will be reused for multiple message.
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2004/11/49 The Drawback of WEP (2) ► Message Modification The WEP checksum is a linear function of the message.
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2004/11/410 Outline ► Introduction ► IEEE 802.1x Std and RSN ► Man-in-Middle, Session Hijack attack ► Proposed solution ► Conclusion
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2004/11/411 IEEE 802.1x and RSN ► IEEE 802.1x is a security framework must provide network access authentication. ► RSN (Robust Security Network) provides mechanisms to restrict network connectivity to authorized entities only via 802.1x.
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2004/11/412 IEEE 802.1x Setup ► Supplicant: An entity use a service via a port on the Authenticator. ► Authenticator: A service provider. ► AAA Server: A central authentication server which directs the Authenticator to provide the service after successful authentication.
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2004/11/413 802.11 Association
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2004/11/414 A Typical Authentication Session using EAP EAPOLRADIUS EAPOL Start
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2004/11/415 Extensible Authentication Protocol (EAP) ► EAP is built around the challenge-response communication paradigm. ► Four type messages: EAP Request, EAP Response, EAP Success, EAP Failure.
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2004/11/416 EAPOL ► The EAP Over Lan (EAPOL) protocol carries the EAP packets between authenticator and supplicant. ► An EAPOL key message provides a way of communicating a higher-layer negotiated session key.
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2004/11/417 RADIUS ► Remote Authentication Dial-In User Service (RADIUS) Protocol. ► The Authentication server and the authenticator communicate using the RADIUS.
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2004/11/418 Dual Port Model ► The AP (Authenticator) must permit the EAP traffic before the authentication succeeds.
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2004/11/419 802.11/1x State Machine
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2004/11/420 Outline ► Introduction ► IEEE 802.1x Std and RSN ► Man-in-Middle, Session Hijack attack ► Proposed solution ► Conclusion
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2004/11/421 Attack ► MIM (Man-in-Middle) attack. ► Session Hijacking. ► Denial of Service (DoS).
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2004/11/422 Man-in-Middle ► An attacker forge this packet on behalf of the authenticator and potentially start a simple Man-in-Middle attack.
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2004/11/423 Session Hijacking ► The session hijack by spoofing a 802.11 MAC disassociate message.
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2004/11/424 Denial of Service (DoS) ► EAPOL Logoff, EAPOL Start message spoofing. ► EAP failure message spoofing. ► Spoofing of 802.11 management frames. ► Large number of associate request.
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2004/11/425 Outline ► Introduction ► IEEE 802.1x Std and RSN ► Man-in-Middle, Session Hijack attack ► Proposed solution ► Conclusion
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2004/11/426 Per-packet Authenticity and Integrity ► Lack of per-packet authenticity and integrity in IEEE 802.11 frames has been a key contributor in many of the protocol ’ s security problems. ► There are currently no plans by the IEEE to add integrity protection to management frame. ► The session hijack attack primarily exploited.
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2004/11/427 Authenticity and Integrity of EAPOL messages ► Addition of an EAP authenticator attribute.
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2004/11/428 Outline ► Introduction ► IEEE 802.1x Std and RSN ► Man-in-Middle, Session Hijack attack ► Proposed solution ► Conclusion
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2004/11/429 Conclusion ► Because the transport medium is shared, permits attackers easy and unconstrained access. ► Our attacks demonstrate that the current RSN architecture does not provide strong access control and authentication.
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2004/11/430 Reference 1. 1. Arunesh Mishra, William A. Arbaugh, “ An Initial security analysis of the IEEE 802.1x Standard ”. 2. 2. N.Borisov, L.Goldberg, D.Wagner, “ Intercepting Mobile Communications: The Insecurity of 802.11 ”. Proc., Seventh Annual International Conference on Mobile Computing and Networking, July, 2001, pages 180-188. 3. 3. IEEE, Lan man standard of the ieee computer society. Wireless lan media access control and physical layer specification. IEEE standard 802.11, 1997.
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