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Versions: 00 01 02 03 04 05 06 07 RFC 4016

   PANA Working Group
   Internet Draft                                      M. Parthasarathy
   Document: draft-ietf-pana-threats-eval-05.txt                  Nokia
   Expires: December 2004                                     June 2004



      Protocol for Carrying Authentication and Network Access Threat
                    Analysis and Security Requirements



Status of this Memo

   By submitting this Internet-Draft, I certify that any applicable
   patent or other IPR claims of which I am aware have been disclosed,
   and any of which I become aware will be disclosed, in accordance with
   RFC 3668.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on December 2004.

Copyright Notice

   Copyright (C) The Internet Society (2004). All Rights Reserved.


Abstract

   The PANA (Protocol for Carrying Authentication for Network Access)
   Working Group is developing methods for authenticating clients to the
   access network using IP based protocols. This document discusses the
   threats to such protocols. The security requirements arising out of
   these threats will be used as additional input to the PANA WG for
   designing the IP based network access authentication protocol.


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Table of Contents

   1.0 Introduction..................................................2
   2.0 Keywords......................................................2
   3.0 Terminology and Definitions...................................3
   4.0 Usage Scenarios...............................................4
   5.0 Trust Relationships...........................................4
   6.0 Threat Scenarios..............................................6
      6.1 PAA Discovery..............................................6
      6.2 Authentication.............................................7
      6.3 PaC leaving the network...................................10
      6.4 Service theft.............................................11
      6.5 PAA-EP communication......................................11
      6.6 Miscellaneous attacks.....................................12
   7.0 Summary of Requirements......................................13
   8.0 Security Considerations......................................14
   9.0 Normative References.........................................14
   10.0 Informative References......................................14
   11.0 Acknowledgments.............................................15
   12.0 Revision Log................................................15
   13.0 Author's Address............................................16
   Intellectual Property Statement..................................16
   Disclaimer of Validity...........................................16
   Copyright Statement..............................................17
   Acknowledgment...................................................17

1.0 Introduction

   The PANA (Protocol for Carrying Authentication for Network Access)
   Working Group is developing methods for authenticating clients to the
   access network using IP based protocols. This document discusses the
   threats to such IP based protocols.

   A client wishing to get access to the network must carry on multiple
   steps. First, it needs to discover the IP address of the PANA
   authentication agent (PAA) and then execute an authentication
   protocol to authenticate itself to the network. Once the client is
   authenticated, there might be other messages exchanged during the
   lifetime of the network access. This document discusses the threats
   in these steps without discussing any solutions. The requirements
   arising out of these threats will be used as input to the PANA
   Working Group.

2.0 Keywords




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   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [KEYWORDS].


3.0 Terminology and Definitions

   Client Access Device

      A network element (e.g., notebook computer, PDA, etc.) that
      requires access to a provider's network.

   Network Access Server (NAS)

      Network device that provides access to the network.

   PANA Client (PaC)

      An entity in the edge subnet, who is wishing to obtain network
      access from a PANA authentication agent within a network. A PANA
      client is associated with a device and a set of credentials to
      prove its identity within the scope of PANA.

   PANA Authentication Agent (PAA)

      An entity whose responsibility is to authenticate the PANA client
      and grant network access service to the client's device.

   Authentication Server (AS)

      An entity that authenticates the PANA client. It may be co-located
      with PANA authentication agent or part of the back-end
      infrastructure.

   Device Identifier (DI)

      The identifier used by the network as a handle to control and
      police the network access of a client. Depending on the access
      technology, identifier might contain any of IP address, link-layer
      address, switch port number, etc. of a device. PANA authentication
      agent keeps a table for binding device identifiers to the PANA
      clients. At most one PANA client should be associated with a DI on
      a PANA authentication agent.

   Enforcement Point (EP)






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      A node that is capable of filtering packets sent by the PANA
      client using the DI information authorized by PANA authentication
      agent.

   Compound methods

      Authentication protocol where, sequence of methods are used one
      after an other or where methods are tunneled inside an another
      independently established tunnel between the client and server
      [TUN-EAP].

4.0 Usage Scenarios

   PANA is intended to be used in an environment where there is no a
   priori trust relationship or security association between the PaC and
   other nodes like PAA and EP. In these environments, one may observe
   the following.

       o The link between PaC and PAA may be a shared medium
          (e.g., Ethernet) or may not be a shared medium (e.g., DSL
          network).

       o All the PaCs may be authenticated to the access network at
          layer 2 (e.g., 3GPP2 CDMA network) and share a security
          association with layer 2 authentication agent (e.g., BTS). The
          PaCs still don't trust each other i.e., any PaC can pretend to
          be a PAA, spoof IP addresses and launch various other attacks.

   The scenarios mentioned above affect the threat model of PANA. This
   document discusses the various threats in the context of the above
   network access scenarios for a better understanding of the threats.
   In the following discussion, any reference to a link that is not
   shared (or non-shared) is assumed to be physically secure. If such an
   assumption cannot be made about the link, then it becomes the same as
   the link that is being shared by more than one node.

5.0 Trust Relationships

   PANA authentication involves a client (PaC), PANA agent (PAA),
   Authentication server (AS) and an Enforcement point (EP). The AS here
   refers to the AAA server that resides in the home realm of the PaC.

   The entities that have a priori trust relationships before PANA
   begins are as follows.

     1) PAA and AS: The PaC belonging to the same administrative domain
        as the AS, often needs to use resources provided by PAA that
        belongs to another administrative domain. PAA authenticates the
        PaC before providing local network access. The credentials


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        provided by PaC for authentication may or may not be understood
        by PAA. If PAA does not understand the credentials, it needs to
        communicate with the AS in a different domain to verify the
        credentials. The threats in the communication path between PAA
        and AS are already covered in [RAD-EAP]. To counter these
        threats, the communication between PAA and AS are secured using
        a static or dynamic security association.

     2) PAA and EP: The PAA and EP belong to the same administrative
        domain. Hence, the network operator can setup a security
        association to protect the traffic exchanged between them. This
        document discusses the threats in this path.

     3) PaC and AS: The PaC and AS belong to the same administrative
        domain and share a trust relationship. When PaC uses a different
        domain than its home for network access, it provides its
        credentials to the PAA in the visited network for
        authentication. The information provided by PaC traverses the
        PaC-PAA path and   PAA-AS path. The threats in PAA-AS path are
        already discussed in [RAD-EAP]. This document discusses the
        threats in PaC-PAA path.

   It is possible that some of the entities like PAA, AS and EP are
   co-located. In those cases, it can be safely assumed that there are
   no significant external threats in their communication.

   The entities that do not have any trust relationship before PANA
   begins are as follows.

     1) PaC and PAA: The PaC and PAA normally belong to two different
        administrative domains. They do not necessarily share a trust
        relationship initially. They establish a security association in
        the process of authentication. All messages exchanged between
        PaC and PAA are subject to various threats, which are discussed
        in this document.

     2) PaC and EP: The EP belongs to the same administrative domain as
        PAA and hence PaC and EP do not necessarily share a trust
        relationship initially. When PaC is successfully authenticated,
        it may result in key establishment between PaC and PAA, which
        can be further used to secure the link between PaC and EP. For
        example, EAP keying framework [EAP-KEY], defines a three party
        EAP exchange where the clients derive the transient sessions
        keys to secure the link between the peer and NAS in their final
        step. Similarly, PANA will provide the ability to establish keys
        between PaC and EP that can be used to secure the link further.
        This is further discussed in section 6.4 below.




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6.0 Threat Scenarios

   The PANA authentication client (PaC) needs to discover the PAA first.
   This involves either sending solicitations or waiting for
   advertisements. Once it has discovered the PAA, it will lead to
   authentication exchange with PAA. Once the access is granted, PaC
   will most likely exchange data with other nodes in the Internet.
   These steps are vulnerable to man-in-the-middle (MITM), denial of
   service (DoS), and service theft attacks, which are discussed below.

   The threats are grouped by the various stages the client goes through
   to gain access to the network. Section 6.1 discusses the threats
   related to PAA discovery. Section 6.2 discusses the threats related
   to authentication itself. Section 6.3 discusses the threats involved
   while leaving the network. Section 6.4 discusses service theft.
   Section 6.5 discusses the threats in PAA-EP path. Section 6.6
   discusses the miscellaneous threats.

   Some of the threats discussed in the following sections may be
   specific to shared links. The threat may be absent on non-shared
   links. Hence, it is only required to prevent the threat on shared
   links. Instead of specifying a separate set of requirements for
   shared links and non-shared links, this document just specifies one
   set of requirements with the following wording: "PANA MUST be able to
   prevent threat X". This means that the PANA protocol should be
   capable of preventing threat X. The feature that prevents threat X
   may or may not be used depending on the deployment.

6.1 PAA Discovery

   The PAA is discovered by sending solicitations or receiving
   advertisements. Following are the possible threats.

   T6.1.1: A malicious node can pretend to be a PAA by sending a
           spoofed advertisement.

   In existing dial-up networks, the clients authenticate to the network
   but generally do not verify the authenticity of the messages coming
   from Network Access Server (NAS). This mostly works because the link
   between the device and the NAS is not shared with other nodes
   (assuming that nobody tampers with the physical link), and clients
   trust the NAS and the phone network to provide the service. Spoofing
   attacks are not present in this environment because the PaC may
   assume that the other end of the link is the PAA.

   In environments where the link is shared, this threat is present as
   any node can pretend to be a PAA. Even if the nodes are authenticated
   at layer 2, this threat is present. It is difficult to protect the


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   discovery process, as there is no a priori trust relationship between
   PAA and PaC. In deployments where EP can police the packets that are
   sent among the PaCs, it is possible to filter out the unauthorized
   PANA packets (e.g., PAA advertisements sent by PaC) and prevent this
   threat.

   The advertisement may be used to include other information like
   supported authentication methods etc., besides the discovery of the
   PAA itself. This can lead to a bidding down attack, as a malicious
   node can send a spoofed advertisement with capabilities that indicate
   less secure authentication methods than what the real PAA supports,
   thereby fooling the PaC into negotiating a less secure authentication
   method than what would otherwise be available.

   Requirement 1

   PANA MUST not assume that the discovery process is protected.

6.2 Authentication

   This section discusses the threats specific to the authentication
   protocol. Section 6.2.1 discusses the possible threat associated with
   success/failure indications that are transmitted to PaC at the end of
   the authentication. Section 6.2.2 discusses the man-in-the-middle
   attack when compound methods are used. Section 6.2.3 discusses the
   replay attack and section 6.2.4 discusses about the device identifier
   attack.

6.2.1 Success or Failure Indications

   Some authentication protocols e.g., EAP, have a special message to
   indicate success or failure. An attacker can send false
   authentication success or failure message to the PaC. By sending
   false failure message, the attacker can prevent the client from
   accessing the network. By sending false success message, the attacker
   can prematurely end the authentication exchange effectively denying
   service for the PaC.

   If the link is not shared, then this threat is absent as ingress
   filtering can prevent the attacker from impersonating as the PAA.

   If the link is shared, it is easy to spoof these packets. If layer 2
   provides per-packet encryption with pair-wise keys, it might make it
   hard for the attacker to guess the success or failure packet that the
   client would accept. Even if the node is already authenticated at
   layer 2, it can still pretend to be a PAA and spoof the success or
   failure.




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   This attack is possible if the success or failure indication is not
   protected using a security association between the PaC and the PAA.
   In order to avoid this attack, the PaC and PAA should mutually
   authenticate each other. In the process of mutually authenticating
   each other, they should be able to establish keys to protect the
   success or failure indications. It may not be possible to protect the
   success or failure indication always as the keys may not be
   established prior to transmitting the success or failure packet. If
   the client is re-authenticating to the network, it can use the
   previously established security association to protect the success or
   failure indications. Similarly, all PANA messages that are exchanged
   during the authentication prior to key establishment may not be
   protected.

   Requirement 2

   PANA MUST be able to mutually authenticate the PaC and PAA. PANA MUST
   be able to establish keys between the PaC and PAA to protect the PANA
   messages.

6.2.2 MITM attack

   A malicious node can claim to be PAA to the real PaC and claim to be
   PaC to the real PAA. This is a man in the middle (MITM) attack where
   the PaC is fooled to think that it is communicating with real PAA and
   the real PAA is fooled to think that it is communicating with real
   PaC.

   If the link is not shared, this threat is absent as ingress filtering
   can prevent the attacker from acting as man in the middle.

   If the link is shared, this threat is present. Even if the layer 2
   provides per-packet protection, the attacker can act as man in the
   middle and launch this attack. An instance of MITM attack, when
   compound authentication methods are used is described in [TUN-EAP].
   In these attacks, the server first authenticates to the client. As
   the client has not proven its identity yet, the server acts as the
   man-in-the-middle, tunneling the identity of the legitimate client to
   gain access to the network. The attack is possible because there is
   no verification that the same entities participated among the
   compound methods. It is not possible to do such verification if
   compound methods are used without being able to create cryptographic
   binding among them. This implies that PANA will be vulnerable to such
   attacks if compound methods are used without being able to
   cryptographically bind them. Note that the attack does not exist if
   the keys derived during the tunnel establishment are not used for
   authenticating the client e.g., tunnel keys are used for just
   protecting the identity of the client.



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   Requirement 3

   When compound authentication methods are used in PANA, the methods
   MUST be cryptographically bound.


6.2.3 Replay Attack

   A malicious node can replay the messages that caused authentication
   failure or success at a later time to create false failures or
   success. The attacker can also potentially replay other messages of
   the PANA protocol to deny service to the PaC.

   If the link is not shared, this threat is absent as ingress filtering
   can prevent the attacker from impersonating as PAA and replay the
   packets.

   If the link is shared, this threat is present. If the packets are
   encrypted at layer 2 using pair-wise keys, it will make it hard for
   the attacker to learn the unencrypted (i.e., original) packet that
   needs to be replayed. Even if layer 2 provides replay protection, the
   attacker can still replay the PANA messages (layer 3) for denying
   service to the client.

   Requirement 4

   PANA MUST be able to protect itself against replay attacks.

6.2.4 Device Identifier Attack

   When the client is successfully authenticated, the PAA sends access
   control information to the EP for granting access to the network. The
   access control information typically contains the device identifier
   of the PaC, which is obtained from the IP headers and MAC headers of
   the packets exchanged during the authentication process or carried
   explicitly in the PANA protocol field. The attacker can gain
   unauthorized access into the network using the following steps.

     . An attacker pretends to be a PAA and sends advertisements. PaC
        gets fooled and starts exchanging packets with the attacker.
     . The attacker modifies the IP source address on the packet,
        adjusts the UDP/TCP checksum and forwards the packet to the real
        PAA. It does the same on return packets also.
     . When the real PaC is successfully authenticated, the attacker
        gains access to the network as the packets contained the IP
        address (and potentially the MAC address also) of the attacker.

   If the link is not shared, this threat is absent, as the attacker
   cannot impersonate as PAA and intercept the packets from PaC.


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   If the link is shared, this threat is present. If the layer 2
   provides per-packet protection, it is not possible to change the MAC
   address and hence this threat may be absent in such cases if EP
   filters both on IP and MAC address.

   Requirement 5

   PANA MUST be able to protect the device identifier against spoofing
   when it is exchanged between the PaC and PAA.


6.3 PaC leaving the network

   When the PaC leaves the network, it can inform the PAA before
   disconnecting from the network so that the resources used by PaC can
   be accounted properly. The PAA may also choose to revoke the access
   any time if it deems necessary. Following are the possible threats.

   T6.3.1: A malicious node can pretend to be a PAA and revoke the
           access to PaC.

   T6.3.2: A malicious node can pretend to be a real PaC and transmit a
           disconnect message.

   T6.3.3: The PaC can leave the network without notifying the PAA or EP
           e.g., the Ethernet cable is unplugged, system crash. An
           attacker can pretend to be the PaC and start using the
           network.

   If the link is not shared, the threats T6.3.1 and T6.3.2 are absent.
   The threat T6.3.3 may still be present. If there is no layer 2
   indication or the layer 2 indication cannot be relied up on, then the
   threat T6.3.3 is still present on non-shared links.

   If the link is shared, all of the above threats are present as any
   node on the link can spoof the disconnect message. Even if the layer
   2 has per-packet authentication, the attacker can pretend to be a PaC
   e.g., by spoofing the IP address, and disconnect from the network.
   Similarly, any node can pretend to be a PAA and revoke the access to
   the PaC. Hence, T6.3.1 and T6.3.2 are possible even on links where
   layer 2 is secured. The threat T6.3.3 can be prevented if layer 2
   provides per-packet authentication. The attacker cannot subsume the
   PaC that left the network without knowing the keys that protect the
   packet at layer 2.

   Requirement 6




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   PANA MUST be able to protect disconnect and revocation messages. PANA
   MUST NOT depend on the PaC sending a disconnect message.


6.4 Service theft

   An attacker can gain unauthorized access into the network by stealing
   the service from another client. Once the real PaC is successfully
   authenticated, EP will have filters in place to prevent unauthorized
   access into the network. The filters will be based on something that
   will be carried on every packet. For example, the filter could be
   based on IP and MAC address where the packets will be dropped unless
   the packets coming with certain IP address match the MAC address
   also. Following are the possible threats.

   T6.4.1: Attacker can spoof both the IP and MAC address of an
           authorized client to gain unauthorized access. Attacker can
           launch this attack easily by just sniffing the wire for IP
           and MAC address. This lets the attacker use the network
           without any authorization, getting a free service.

   T6.4.2: The PaC can leave the network without notifying the PAA or EP
           e.g., the Ethernet cable is unplugged, system crash. An
           attacker can pretend to be the PaC and start using the
           network.

   If the link is not shared, T6.4.1 is absent as there is only one
   client on the link and ingress filtering can prevent the use of
   authorized IP and MAC address by the attacked on another link.

   If the link is shared, both the threats are present. If layer 2
   provides per-packet protection using pair-wise keys, both the threats
   can be prevented.

   Requirement 7

   PANA MUST securely bind the authenticated session to the device
   identifier of the client, to prevent service theft. PANA MUST be able
   to bootstrap a shared secret between the PaC and PAA which can be
   further used to setup a security association between PaC and EP to
   provide cryptographic protection against service theft.

6.5 PAA-EP communication

   After a successful authentication, the PAA needs to communicate the
   access control information of the PaC to EP so that PaC will be
   allowed to access the network. The information communicated would
   contain at least the device identifier of the PaC. If strong security
   is needed, PAA will communicate a shared secret known only to PaC and


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   PAA, for setting up a security association between PaC and EP.
   Following are the possible threats.

   T6.5.1: Attacker can eavesdrop to learn the information communicated
           between PAA and EP. The attacker can further use this
           information to spoof the real PaC and also setup an security
           association for gaining access to the network. This threat is
           absent, if the attacker cannot eavesdrop the link e.g., PAA
           and EP are communicating on a separate link from that of
           visiting PaCs.

   T6.5.2: Attacker can pretend to be PAA and send false information to
           EP for gaining access to the network. The attacker has to
           send its own device identifier and also a shared secret in
           the case of stronger security so that EP will let the
           attacker access the network.

   If the communication between PAA and EP is protected, these threats
   are absent.

   Requirement 8

   The communication between the PAA and EP MUST be protected against
   eavesdropping and spoofing attacks.

6.6 Miscellaneous attacks

   T6.6.1: There are various forms of DoS attacks that can be launched
           on the PAA or AS. A few are mentioned below. As it is hard to
           defend against some of the DoS attacks, the protocol should
           be designed carefully to mitigate or prevent such attacks.

              . Attacker can bombard the PAA with lots of
                 authentication requests. If PAA and AS are not
                 collocated, PAA may have to allocate resources to store
                 some state about PaC locally before it receives the
                 response from the backend AS. This can deplete memory
                 resources on PAA.

              . The attacker can force the PAA or AS to make
                 computationally intensive operations with minimal
                 effort, that can deplete the CPU resources of the PAA
                 or AS.

   T6.6.2: PaC acquires an IP address by using stateful or stateless
           mechanisms before PANA authentication begins [PANAREQ]. When
           the IP addresses are assigned before the client
           authentication, it opens up the possibility of DoS attacks
           where unauthenticated malicious nodes can deplete the IP


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           address space by acquiring multiple IP addresses, or denying
           allocation to others by responding to every duplicate address
           detection (DAD) query.

           Depleting a /64 IPv6 link-local address space or a /8 RFC1918
           private address space requires a brute-force attack. Such an
           attack is part of a DoS class that can equally target the
           link capacity or the CPU cycles on the target system by
           bombarding arbitrary packets. Therefore solely handling the
           IP address depletion attack is not going to improve the
           security as a more general solution is needed to tackle the
           whole class of brute-force attacks.

           The DAD attack can be prevented by deploying secure address
           resolution that does not depend on the client authentication,
           such as [SEND]. The attack may also be prevented if the EP is
           placed in between the PaCs to monitor the ND/ARP activity and
           detect DAD attacks (excessive NA/ARP replies). If none of
           these solutions are applicable to a deployment, the PaCs can
           send arbitrary packets to each other without going through
           the EP which enables a class of attacks that are based on
           interfering with the PANA messaging (See T6.1.1). Since there
           will always be an unhandled threat in this class (e.g.,
           insecure discovery), addressing DAD attack is not going to
           improve the overall security.

7.0 Summary of Requirements

        1. PANA MUST not assume that the discovery process is protected.

        2. PANA MUST be able to mutually authenticate the PaC and PAA.
          PANA MUST be able to establish keys between the PaC and PAA
          to protect the PANA messages.

        3. When compound authentication methods are used in PANA, the
          methods MUST be cryptographically bound.

        4. PANA MUST be able to protect itself against replay attacks.

        5. PANA MUST be able to protect the device identifier against
          spoofing when it is exchanged between the PaC and PAA.

        6. PANA MUST be able to protect disconnect and revocation
          messages. PANA MUST NOT depend on the PaC sending a
          disconnect message.

        7. PANA MUST securely bind the authenticated session to the
          device identifier of the client, to prevent service theft.
          PANA MUST be able to bootstrap a shared secret between the


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          PaC and PAA which can be further used to setup a security
          association between PaC and EP to provide cryptographic
          protection against service theft.

        8. The communication between the PAA and EP MUST be protected
          against eavesdropping and spoofing attacks.

8.0 Security Considerations

   This document discusses various threats with IP based network access
   authentication protocol.

9.0 Normative References

   [KEYWORDS] S. Bradner, "Key words for use in RFCS to indicate
   requirement levels", RFC 2119, March 1997.

10.0 Informative References

   [PANAREQ] A. Yegin et al., "Protocol for Carrying Authentication for
   Network Access (PANA) Requirements and Terminology",
   draft-ietf-pana-requirements-08.txt.

   [RADIUS] C. Rigney et. al, "Remote Authentication Dial In User
   Service", RFC2865, June 2000.

   [EAP-KEY] B. Aboba et. al, "EAP keying framework",
   draft-ietf-eap-keying-00.txt.

   [ADDRCONF] S. Thomson et. al, "IPv6 Stateless Address
   Autoconfiguration", RFC2462, December 1998.

   [RAD-EAP] B. Aboba, et. al, "Radius support for Extensible
   authentication protocol", RFC3579, September 2003.

   [TUN-EAP] J. Puthenkulam et. al, "The compound authentication
   binding problem", draft-puthenkulam-eap-binding-04.txt.

   [IPSEC] S. Kent et. al, "Security architecture for the Internet
   Protocol", RFC 2401, November 1998.

   [SEND] J. Arkko et. al, "Secure Neighbor Discovery (SEND)",
   draft-ietf-send-ndopt-05.txt.

   [IEEE-802.11i] Institute of Electrical and Electronics Engineers
   "Unapproved Draft Supplement to Standard for Telecommunications and
   Information Exchange Between systems - LAN/MAN Specific Requirements
   - Part 11: Wireless LAN Medium Access Control (MAC) and Physical



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   Layer (PHY) Specifications: Specification for Enhanced Security",
   IEEE Draft 802.11i (work in progress), 2003.

   [IEEE-802.11] Institute of Electrical and Electronics Engineers,
   "Information Technology - Telecommunications and Information Exchange
   between Systems - Local and Metropolitan Area Network - Specific
   Requirements - Part 11: Wireless LAN Medium Access  Control (MAC) and
   Physical Layer (PHY) Specifications", IEEE Standard 802.11, 1999.

11.0 Acknowledgments

   The author would like to thank the following people (in no specific
   order) for providing valuable comments: Alper Yegin, Basavaraj Patil,
   Pekka Nikander, Bernard Aboba, Francis Dupont, Michael Thomas,
   Yoshihiro Ohba, Gabriel Montenegro, Tschofenig Hannes, Bill
   Sommerfeld, N. Asokan, Pete McCan, Derek Atkins and Thomas Narten.

12.0 Revision Log

   Changes between 04 and 05

   -Updates after AD review.

   Changes between 03 and 04

   -Added a new requirement for the disconnect notification.
   -Trust relationship section was rewritten.
   -Device identifier attack requirements was rewritten.
   -Service theft requirement was rewritten.
   -Added a new section for PAA-EP threats.

   Changes between revision 02 and 03

  -Changed Requirement 1 to include text about weak authentication
  suites.
  -Rearranged the order of definitions in terminology section.
  -Removed some confusing text with respect to IPsec from the Service
  theft section.

   Changes between revision 01 and 02

  -Renamed the section "Assumptions" to "Trust relationships" and added
  more text to clarify the relationship between PaC and EP.
  -Added more text for threats in the path between PAA and AS.
  -Merged the "Type of Attacks" section into "Threat Scenarios"
  -Removed the requirement on DoS attack.
  -Reworded most of the requirements.

  Changes between revision 00 and 01


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  -Removed unused terms from section 3.0.
  -Removed identity protection as a threat after feedback from Atlanta
  IETF55 meeting.
  -Renamed the section "Attacks on Normal Data communication" to
  "Service theft". Removed confidentiality as a requirement from that
  section.
  -Added a new threat "Device Identifier attack".

13.0 Author's Address

   Mohan Parthasarathy
   Nokia
   313 Fairchild Drive
   Mountain View, CA-94303

   Email: mohanp@sbcglobal.net


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