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Network Working Group                                          D. Saucez
Internet-Draft                                                     INRIA
Intended status: Informational                                L. Iannone
Expires: April 24, 2014                                Telecom ParisTech
                                                          O. Bonaventure
                                        Universite catholique de Louvain
                                                        October 21, 2013


                         LISP Threats Analysis
                     draft-ietf-lisp-threats-08.txt

Abstract

   This document proposes a threat analysis of the Locator/Identifier
   Separation Protocol (LISP) if deployed in the Internet.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 24, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  On-path Attackers . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Off-Path Attackers: Reference Environment . . . . . . . . . .   4
   4.  Attack vectors  . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Configured EID-to-RLOC mappings . . . . . . . . . . . . .   5
     4.2.  EID-to-RLOC Cache . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Attacks using the data-plane  . . . . . . . . . . . . . .   6
       4.3.1.  Attacks not leveraging on the LISP header . . . . . .   6
       4.3.2.  Attacks leveraging on the LISP header . . . . . . . .   8
     4.4.  Attacks using the control-plane . . . . . . . . . . . . .  11
       4.4.1.  Attacks with Map-Request messages . . . . . . . . . .  11
       4.4.2.  Attacks with Map-Reply messages . . . . . . . . . . .  12
       4.4.3.  Attacks with Map-Register messages  . . . . . . . . .  13
       4.4.4.  Attacks with Map-Notify messages  . . . . . . . . . .  14
   5.  Attack categories . . . . . . . . . . . . . . . . . . . . . .  14
     5.1.  Intrusion . . . . . . . . . . . . . . . . . . . . . . . .  14
       5.1.1.  Description . . . . . . . . . . . . . . . . . . . . .  14
       5.1.2.  Vectors . . . . . . . . . . . . . . . . . . . . . . .  14
     5.2.  Denial of Service (DoS) . . . . . . . . . . . . . . . . .  14
       5.2.1.  Description . . . . . . . . . . . . . . . . . . . . .  14
       5.2.2.  Vectors . . . . . . . . . . . . . . . . . . . . . . .  15
     5.3.  Subversion  . . . . . . . . . . . . . . . . . . . . . . .  15
       5.3.1.  Description . . . . . . . . . . . . . . . . . . . . .  15
       5.3.2.  Vectors . . . . . . . . . . . . . . . . . . . . . . .  15
   6.  Note on privacy . . . . . . . . . . . . . . . . . . . . . . .  16
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  17
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     10.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Appendix A.  Document Change Log  . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   The Locator/ID Separation Protocol (LISP) is defined in [RFC6830].
   The present document assesses the security level and identifies
   security threats in the LISP specification if LISP is deployed in the
   Internet (i.e., a public non-trustable environment).  As a result of
   the performed analysis, the document discusses the severity of the
   threats and proposes recommendations to reach the same level of
   security in LISP than in Internet today (e.g., without LISP).

   The document is composed of three main parts: the first discussing
   the LISP data-plane; while the second discussing the LISP control-



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   plane.  The final part summarizes the recommendations to prevent the
   identified threats.

   The LISP data-plane consists of LISP packet encapsulation,
   decapsulation, and forwarding and includes the map cache data
   structures used to perform these operations.

   The LISP control-plane consists in the mapping distribution system,
   which can be one of the mapping distribution systems proposed so far
   (e.g., [RFC6830], [I-D.ietf-lisp-ddt], [RFC6836], [RFC6833],
   [I-D.meyer-lisp-cons], and [RFC6837]), and the Map-Request, Map-
   Reply, Map-Register, and Map-Notification messages.

   This document does not consider all the possible uses of LISP as
   discussed in [RFC6830].  The document focuses on LISP unicast,
   including as well LISP Interworking [RFC6832], LISP-MS [RFC6833], and
   LISP Map-Versioning [RFC6834].  The reading of these documents is a
   prerequisite for understanding the present document.

   Unless otherwise stated, the document assumes a generic IP service
   and does not discuss the difference, from a security viewpoint,
   between using IPv4 or IPv6.

2.  On-path Attackers

   On-path attackers are attackers that are able to capture and modify
   all the packets exchanged between an Ingress Tunnel Router (ITR) and
   an Egress Tunnel Router (ETR).  To cope with such an attacker,
   cryptographic techniques such as those used by IPSec ([RFC4301]) are
   required.  As with IP, LISP relies on higher layer cryptography to
   secure packet payloads from on path attacks, so this document does
   not consider on-path attackers in this document.

   Similarly, a time-shifted attack is an attack where the attacker is
   temporarily on the path between two communicating hosts.  While it is
   on-path, the attacker sends specially crafted packets or modifies
   packets exchanged by the communicating hosts in order to disturb the
   packet flow (e.g., by performing a man in the middle attack).  An
   important issue for time-shifted attacks is the duration of the
   attack once the attacker has left the path between the two
   communicating hosts.  We do not consider time-shifted attacks in this
   document.









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3.  Off-Path Attackers: Reference Environment

   The reference environment shown in the figure below is considered
   throughout this document.  There are two hosts attached to LISP
   routers: HA and HB.  HA is attached to the two LISP xTRs LR1 and LR2,
   which in turn are attached to two different ISPs.  HB is attached to
   the two LISP xTRs LR3 and LR4.  HA and HB are the EIDs of the two
   hosts.  LR1, LR2, LR3, and LR4 are the RLOCs of the xTRs.  PxTR is a
   proxy xTR and MR/MS plays the roles of Map Server and/or Map
   Resolver.

                +-----+
                | HA  |
                +-----+
                   | EID: HA
                   |
               -----------------
                   |          |
                +-----+    +-----+
                | LR1 |    | LR2 |
                +-----+    +-----+
                   |          |
                   |          |
                +-----+    +-----+
                |ISP1 |    |ISP2 |
                +-----+    +-----+
                   |          |
   +------+     +----------------+     +-----+
   | PxTR |-----|                |-----| SA  |
   +------+     |                |     +-----+
                |    Internet    |
   +-------+    |                |     +-----+
   | MR/MS |----|                |-----| NSA |
   +-------+    +----------------+     +-----+
                   |          |
                +-----+    +-----+
                | LR3 |    | LR4 |
                +-----+    +-----+
                   |          |
               -------------------
                              |
                              | EID: HB
                           +-----+
                           | HB  |
                           +-----+

                        Figure 1: Reference Network




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   We consider two off-path attackers with different capabilities:

   SA  is an off-path attacker that is able to send spoofed packets,
       i.e., packets with a different source IP address than its
       assigned IP address.  SA stands for Spoofing Attacker.

   NSA is an off-path attacker that is only able to send packets whose
       source address is its assigned IP address.  NSA stands for Non
       Spoofing Attacker.

   It should be noted that with LISP, packet spoofing is slightly
   different than in the current Internet.  Generally the term "spoofed
   packet" indicates a packet containing a source IP address that is not
   the one of the actual originator of the packet.  Since LISP uses
   encapsulation, the spoofed address could be in the outer header as
   well as in the inner header, this translates in two types of
   spoofing:

   EID Spoofing:  the originator of the packet puts in it a spoofed EID.
         The packet will be normally encapsulated by the ITR of the site
         (or a PITR if the source site is not LISP enabled).

   RLOC Spoofing:  the originator of the packet generates directly a
         LISP-encapsulated packet with a spoofed source RLOC.

   Note that the two types of spoofing are not mutually exclusive,
   rather all combinations are possible and could be used to perform
   different kind of attacks.

   In the reference environment, both SA and NSA attackers are capable
   of sending LISP encapsulated data packets and LISP control packets.
   This means that SA is able to perform both RLOC and EID spoofing
   while NSA can only perform EID spoofing.  They may also send other
   types of IP packets such as ICMP messages.  We assume that both
   attackers can query the LISP mapping system (e.g., through a public
   Map Resolver) to obtain the mappings for both HA and HB.

4.  Attack vectors

   This section presents techniques that can be used by attackers to
   succeed attacks leveraging the LISP protocol and architecture.  This
   section focuses on the techniques while Section 5 presents the
   attacks that can be succeeded while using these techniques.

4.1.  Configured EID-to-RLOC mappings

   Each xTR maintains a set of configured mappings related to the EID-
   Prefixes that are "behind" the xTR [RFC6830].  Where "behind" means



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   that at least one of the xTR's globally visible IP addresses is a
   RLOC for those EID-Prefixes.

   As these mappings are determined by configuration.  This means that
   the only way to attack this data structure is by gaining privileged
   access to the xTR.  As such, it is out of the scope of LISP to
   propose any mechanism to protect routers and, hence, it is no further
   analyzed in this document.

4.2.  EID-to-RLOC Cache

   The EID-to-RLOC Cache (also called the Map-Cache) is the data
   structure that stores a copy of the mappings retrieved from a remote
   ETR's mapping via the LISP control-plane.  Attacks against this data
   structure could happen either when the mappings are first installed
   in the cache or by corrupting (poisoning) the mappings already
   present in the cache.

   This document calls "cache poisoning attack", any attack that alters
   the EID-to-RLOC Cache.  Cache poisoning attacks are use to alter (any
   combination of) the following parts of mapping installed in the EID-
   to-RLOC Cache:

   o  EID prefix

   o  RLOC list

   o  RLOC priority

   o  RLOC weight

   o  RLOC reachability

   o  Mapping TTL

   o  Mapping version

   o  Mapping Instance ID

4.3.  Attacks using the data-plane

   The data-plane is constituted of the operations of encapsulation,
   decapsulation, and forwarding as well as the content of the EID-to-
   RLOC Cache and configured EID-to-RLOC mappings as specified in the
   original LISP document ([RFC6830]).

4.3.1.  Attacks not leveraging on the LISP header




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   An attacker can inject packets into flows without using the LISP
   header, i.e., with the N, L, E, V, and I bits ([RFC6830]).

   Taking notation of the reference environment notation (Figure 1), to
   inject a packet in the HA->HB flow, a spoofing off-path attacker (SA)
   could send a LISP encapsulated packet whose source is set to LR1 or
   LR2 and destination LR3 or LR4.  The packet will reach HB as if the
   packet was sent by host HA.  This is not different from today's
   Internet where a spoofing off-path attacker may inject data packets
   in any flow.  A non-spoofing off-path attacker (NSA) could only send
   a packet whose source address is set to its assigned IP address.  The
   destination address of the encapsulated packet could be LR3 or LR4.

4.3.1.1.  Gleaning Attacks

   In order to reduce the time required to obtain a mapping, [RFC6830]
   proposes the gleaning mechanism that allows an ITR to learn a mapping
   from the LISP data encapsulated packets and the Map-Request packets
   that it receives.  LISP data encapsulated packet contains a source
   RLOC, destination RLOC, source EID and destination EID.  When an ITR
   receives a data encapsulated packet coming from a source EID for
   which it does not already know a mapping, it may insert the mapping
   between the source RLOC and the source EID in its EID-to-RLOC Cache.
   Gleaning could also be used when an ITR receives a Map-Request as the
   Map-Request also contains a source EID address and a source RLOC.
   Once a gleaned entry has been added to the EID-to-RLOC cache, the
   LISP ITR sends a Map-Request to retrieve the mapping for the gleaned
   EID from the mapping system.  [RFC6830] recommends storing the
   gleaned entries for only a few seconds.

   An attacker can send LISP encapsulated packets to host HB with host
   HA's EID and if the xTRs that serve host HB do not store a mapping
   for host HA at that time.  The xTR will store the gleaned entry and
   use it to return the packets sent by host HB.  In parallel, the ETR
   will send a Map-Request to retrieve the mapping for HA but until the
   reception of the Map-Reply, host HB will exchange packets with the
   attacker instead of HA.














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   Similarly, if an off-path attacker knows that hosts HA and HB that
   resides in different sites will exchange information at time t the
   attacker could send to LR1 (resp. LR3) a LISP data encapsulated
   packet whose source RLOC is its IP address and contains an IP packet
   whose source is set to HB (resp. HA).  The attacker chooses a packet
   that will not trigger an answer, for example the last part of a
   fragmented packet.  Upon reception of these packets, LR1 and LR3
   install gleaned entries that point to the attacker.  If host HA is
   willing to establishes a flow with host HB at that time, the packets
   that they exchange will pass through the attacker as long as the
   gleaned entry is active on the xTRs.

   By itself, an attack made solely using gleaning cannot last long,
   however it should be noted that with current network capacities, a
   large amount of packets might be exchanged during even a small
   fraction of time.

4.3.1.2.  Threats concerning Interworking

   [RFC6832] defines Proxy-ITR And Proxy-ETR network elements to allow
   LISP and non-LISP sites to communicate.  The Proxy-ITR has
   functionality similar to the ITR, however, its main purpose is to
   encapsulate packets arriving from the DFZ in order to reach LISP
   sites.  A Proxy-ETR has functionality similar to the ETR, however,
   its main purpose is to inject de-encapsulated packets in the DFZ in
   order to reach non-LISP Sites from LISP sites.  As a PITR (resp.
   PETR) is a particular case of ITR (resp. ETR), it is subject to same
   attacks than ITRs (resp. ETR).

   PxTRs can be targeted by attacks aiming to influence traffic between
   LISP and non-LISP sites but also to launch relay attacks.

   It is worth to notice that when PITR and PETR functions are
   separated, attacks targeting nodes that collocate PITR and PETR
   functionality are ineffective.

4.3.2.  Attacks leveraging on the LISP header

   The main LISP document [RFC6830] defines several flags that modify
   the interpretation of the LISP header in data packets.  In this
   section, we discuss how an off-path attacker could exploit this LISP
   header.









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4.3.2.1.  Attacks using the Locator Status Bits

   When the L bit is set to 1, it indicates that the second 32-bits
   longword of the LISP header contains the Locator Status Bits.  In
   this field, each bit position reflects the status of one of the RLOCs
   mapped to the source EID found in the encapsulated packet.  In
   particular, a packet with the L bit set and all Locator Status Bits
   set to zero indicates that none of the locators of the encapsulated
   source EID are reachable.  The reaction of a LISP ETR that receives
   such a packet is not clearly described in [RFC6830].

   An attacker can send a data packet with the L bit set to 1 and some
   or all Locator Status Bits set to zero.  Therefore, by blindly
   trusting the Locator Status Bits communication going on can be
   altered or forced to go through a particular set of locators.

4.3.2.2.  Attacks using the Map-Version bit

   The optional Map-Version bit is used to indicate whether the low-
   order 24 bits of the first 32 bits longword of the LISP header
   contain a Source and Destination Map-Version.  When a LISP ETR
   receives a LISP encapsulated packet with the Map-Version bit set to
   1, the following actions are taken:

   o  It compares the Destination Map-Version found in the header with
      the current version of its own configured EID-to-RLOC mapping, for
      the destination EID found in the encapsulated packet.  If the
      received Destination Map-Version is smaller (i.e., older) than the
      current version, the ETR should apply the SMR procedure described
      in [RFC6830] and send a Map-Request with the SMR bit set.

   o  If a mapping exists in the EID-to-RLOC Cache for the source EID,
      then it compares the Map-Version of that entry with the Source
      Map-Version found in the header of the packet.  If the stored
      mapping is older (i.e., the Map-Version is smaller) than the
      source version of the LISP encapsulated packet, the xTR should
      send a Map-Request for the source EID.

   An off-path attacker could use the Map-Version bit to force an ETR to
   send Map-Request messages.  The attacker could retrieve the current
   source and destination Map-Version for both HA and HB.  Based on this
   information, it could send a spoofed packet with an older Source Map-
   Version or Destination Map-Version.  If the size of the Map-Request
   message is larger than the size of the smallest LISP-encapsulated
   packet that could trigger such a message, this could lead to
   amplification attacks (see Section 4.4.1) so that more bandwidth is
   consumed on the target than the bandwidth necessary at the attacker
   side.



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4.3.2.3.  Attacks using the Nonce-Present and the Echo-Nonce bits

   The Nonce-Present and Echo-Nonce bits are used when verifying the
   reachability of a remote ETR.  Assume that LR3 wants to verify that
   LR1 receives the packets that it sends.  LR3 can set the Echo-Nonce
   and the Nonce-Present bits in LISP data encapsulated packets and
   include a random nonce in these packets.  Upon reception of these
   packets, LR1 will store the nonce sent by LR3 and echo it when it
   returns LISP encapsulated data packets to LR3.

   A spoofing off-path attacker (SA) could interfere with this
   reachability test by sending two different types of packets:

   1.  LISP data encapsulated packets with the Nonce-Present bit set and
       a random nonce and the appropriate source and destination RLOCs.

   2.  LISP data encapsulated packets with the Nonce-Present and the
       Echo-Nonce bits both set and the appropriate source and
       destination RLOCs.  These packets will force the receiving ETR to
       store the received nonce and echo it in the LISP encapsulated
       packets that it sends.

   The first type of packet should not cause any major problem to ITRs.
   As the reachability test uses a 24 bits nonce, it is unlikely that an
   off-path attacker could send a single packet that causes an ITR to
   believe that the ETR it is testing is reachable while in reality it
   is not reachable.  To increase the success likelihood of such attack,
   the attacker should created a massive amount of packets carrying all
   possible nonce values.

   The second type of packet could be exploited to attack the nonce-
   based reachability test.  Consider a spoofing off-path attacker (SA)
   that sends a continuous flow of spoofed LISP data encapsulated
   packets that contain the Nonce-Present and the Echo-Nonce bit and
   each packet contains a different random nonce.  The ETR that receives
   such packets will continuously change the nonce that it returns to
   the remote ITR.  If the remote ITR starts a nonce-reachability test,
   this test may fail because the ETR has received a spoofed LISP data
   encapsulated packet with a different random nonce and never echoes
   the real nonce.  In this case the ITR will consider the ETR not
   reachable.  The success of this test depends on the ratio between the
   amount of packets sent by the legitimate ITR and the spoofing off-
   path attacker (SA).

4.3.2.4.  Attacks using the Instance ID bits

   LISP allows to carry in its header a 24-bits value called "Instance
   ID" and used on the ITR to indicate which local Instance ID has been



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   used for encapsulation, while on the ETR can be used to select the
   forwarding table used for forwarding the decapsulated packet.

   The Instance ID increases exposure to attacks ([RFC6169]) as if an
   off-path attacker can randomly guess a valid Instance ID value to get
   access to network that might not been accessible in normal
   conditions.  However, the impact of such attack is directly on end-
   systems which is is out of the scope of this document.

4.4.  Attacks using the control-plane

   In this section, we discuss the different types of attacks that could
   occur when an off-path attacker sends control-plane packets.  We
   focus on the packets that are sent directly to the ETR and do not
   analyze the particularities of the different LISP indexing sub-
   system.

4.4.1.  Attacks with Map-Request messages

   An off-path attacker could send Map-Request packets to a victim ETR.
   In theory, a Map-Request packet is only used to solicit an answer and
   as such it should not lead to security problems.  However, the LISP
   specification [RFC6830] contains several particularities that could
   be exploited by an off-path attacker.

   The first possible exploitation is the RLOC record P bit.  The RLOC
   record P bit is used to probe the reachability of remote ETRs.  In
   our reference environment, LR3 could probe the reachability of LR1 by
   sending a Map-Request with the RLOC record P bit set.  LR1 would
   reply by sending a Map-Reply message with the RLOC record P bit set
   and the same nonce as in the Map-Request message.

   A spoofing off-path attacker (SA) could use the RLOC record P bit to
   force a victim ETR to send a Map-Reply to the spoofed source address
   of the Map-Request message.  As the Map-Reply can be larger than the
   Map-Request message, there is a risk of amplification attack.
   Considering only IPv6 addresses, a Map-Request can be as small as 40
   bytes, considering one single ITR address and no Mapping Protocol
   Data.  The Map-Reply instead has a proportional to the maximum number
   of RLOCs in a mapping and maximum number of records in a Map-Reply.
   Since up to 255 RLOCs can be associated to an EID-Prefix and 255
   records can be stored in a Map-Reply, the maximum size of a Map-Reply
   is thus above 1 MB, largely bigger than the message sent by the
   attacker.  These numbers are however theoretical values not
   considering transport layer limitations and it is more likely that
   the reply will contain only one record with at most a dozen of
   locators, limiting so the amplification factor.




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   Similarly, if a non-spoofing off-path attacker (NSA) sends a Map-
   Request with the RLOC record P bit set, it will receive a Map-Reply
   with the RLOC record P bit set.

   An amplification attack could be launched by a spoofing off-path
   attacker (SA) as follows.  Consider an attacker SA and EID-Prefix
   192.0.2.0/24 and a victim ITR, SA could send spoofed Map-Request
   messages whose source EID addresses are all the addresses inside
   192.0.2.0/24 and source RLOC address is the victim ITR.  Upon
   reception of these Map-Request messages, the ETR would send large
   Map-Reply messages for each of the addresses inside p/P back to the
   victim ITR.

   The Map-Request message may also contain the SMR bit.  Upon reception
   of a Map-Request message with the SMR bit, an ETR must return to the
   source of the Map-Request message a Map-Request message to retrieve
   the corresponding mapping.  This raises similar problems as the RLOC
   record P bit discussed above except that as the Map-Request messages
   are smaller than Map-Reply messages, the risk of amplification
   attacks is reduced.  This is not true anymore if the ETR append to
   the Map-Request messages its own Map-Records.  This mechanism is
   meant to reduce the delay in mapping distribution since mapping
   information is provided in the Map-Request message.

   Furthermore, appending Map-Records to Map-Request messages allows an
   off-path attacker to generate a (spoofed or not) Map-Request message
   and include in the Map-Reply portion of the message mapping for EID
   prefixes that it does not serve.

   Moreover, attackers can use Map Resolver and/or Map Server network
   elements to perform relay attacks.  Indeed, on the one hand, a Map
   Resolver is used to dispatch Map-Request to the mapping system and,
   on the other hand, a Map Server is used to dispatch Map-Requests
   coming from the mapping system to ETRs that are authoritative for the
   EID in the Map-Request.

4.4.2.  Attacks with Map-Reply messages

   In this section we analyze the attacks that could occur when an off-
   path attacker sends directly Map-Reply messages to ETRs without using
   one of the proposed LISP mapping systems.

   There are two different types of Map-Reply messages:

   Positive Map-Reply:  These messages contain a Map-Record binding an
         EID-Prefix to one or more RLOCs.





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   Negative Map-Reply:  These messages contain a Map-Record for an EID-
         Prefix with an empty locator-set and specifying an action,
         which may be either Drop, natively forward, or Send Map-
         Request.

   Positive Map-Reply messages are used to map EID-Prefixes onto RLOCs.
   Negative Map-Reply messages are used to indicate non-LISP prefixes.
   ITRs can, if needed, be configured to send all traffic destined for
   non-LISP prefixes to a Proxy-ETR.

   Most of the security of the Map-Reply messages depends on the 64 bits
   nonce that is included in a Map-Request and returned in the Map-
   Reply.  If an ETR does not accept Map-Reply messages with an invalid
   nonce, the risk of attack is acceptable given the size of the nonce
   (64 bits).  However, the nonce only confirms that the Map-Reply
   received was sent in response to a Map-Request sent, it does not
   validate the contents of that Map-Reply.

   In addition, an attacker could perform EID-to-RLOC Cache overflow
   attack by de-aggregating (i.e., splitting an EID prefix into
   artificially smaller EID prefixes) either positive or negative
   mappings.

   In presence of malicious ETRs, overclaiming attacks are possible.
   Such an attack happens when and ETR replies to a legitimate Map-
   Request message it received with a Map-Reply message that contains an
   EID-Prefix that is larger than the prefix owned by the site that
   encompasses the EID of the Map-Request.  For instance if the prefix
   owned by the site is 192.0.2.0/25 but the Map-Reply contains a
   mapping for 192.0.2.0/24, then the mapping will influence packets
   destined to other EIDs than the one the LISP site has authority on.

   A malicious ETR might also fragment its configured EID-to-RLOC
   mappings so that ITR's might have to install much more mappings than
   really necessary.  This attack is called de-aggregation attack.

4.4.3.  Attacks with Map-Register messages

   Map-Register messages are sent by ETRs to indicate to the mapping
   system the EID prefixes associated to them.  The Map-Register message
   provides an EID prefix and the list of ETRs that are able to provide
   Map-Replies for the EID covered by the EID prefix.

   As Map-Register messages are protected by an authentication
   mechanism, only a compromised ETR can register itself to its
   allocated Map Server.





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   A compromised ETR can perform an overclaiming attack in order to
   influence the route followed by Map-Requests for EIDs outside the
   scope of its legitimate EID prefix.

   A compromised ETR can also perform a deaggregation attack in order to
   register more EID prefixes than necessary to its Map Servers.

   Similarly, a compromised Map Server can accept invalid registration
   or advertise invalid EID prefix to the indexing sub-system.

4.4.4.  Attacks with Map-Notify messages

   Map-Notify messages are sent by a Map Server to an ETR to acknowledge
   the good reception and processing of a Map-Register message.

   An compromised ETR using EID that it is not authoritative for can
   send a Map-Register with the M-bit set and a spoofed source address
   to force the Map Server to send a Map-Notify message to the spoofed
   address and then succeed a relay attack.  Similarly to the pair Map-
   Request/Map-Reply, the pair Map-Register/Map-Notify is protected by a
   nonce making it hard for an attacker to inject a falsified
   notification to an ETR to make this ETR believe that the registration
   succeeded while it has not.

5.  Attack categories

5.1.  Intrusion

5.1.1.  Description

   With an intrusion attack an attacker gains remote access to some
   resources (e.g., a host, a router, or a network) that are normally
   denied to her.

5.1.2.  Vectors

   Intrusion attacks can be mounted using:

   o  Spoofing EID or RLOCs

   o  Instance ID bits

5.2.  Denial of Service (DoS)

5.2.1.  Description

   A Denial of Service (DoS) attack aims at disrupting a specific
   targeted service either by exhausting the resources of the victim up



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   to the point that it is not able to provide a reliable service to
   legit traffic and/or systems or by exploiting vulnerabilities to make
   the targeted service unable to operate properly.

5.2.2.  Vectors

   Denial of Service attacks can be mounted using

   o  Gleaning

   o  Interworking

   o  Locator Status Bits

   o  Map-Version bit

   o  Nonce-Present and Echo-Nonce bits

   o  Map-Request message

   o  Map-Reply message

   o  Map-Register message

   o  Map-Notify message

5.3.  Subversion

5.3.1.  Description

   With subversion an attacker can gain access (e.g., using
   eavesdropping or impersonation) to restricted or sensitive
   information such as passwords, session tokens, or any other
   confidential information.  This type of attack is usually carried out
   in a way such that the target does not even notice the attack.  When
   the attacker is positioned on the path of the target traffic, it is
   called a Man-in-the-Middle attack.  However, this is not a
   requirement to carry out and eavesdropping attack.  Indeed the
   attacker might be able, for instance through an intrusion attack on a
   weaker system, either to duplicate or even re-direct the traffic, in
   both cases having access to the raw packets.

5.3.2.  Vectors

   Subversion attacks can be mounted using

   o  Gleaning




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   o  Locator Status Bits

   o  Nonce-Present and the Echo-Nonce bits

   o  Map-Request messages

   o  Map-Reply messages

6.  Note on privacy

   As presented by [RFC6973], universal privacy considerations are
   impossible to establish as the privacy definition may vary from one
   to another.  As a consequence, this document does not aim at
   identifying privacy issues related to the LISP protocol but it is
   necessary to highlight that security threats identified in this
   document could play a role in privacy threats as defined in section 5
   of [RFC6973].

7.  IANA Considerations

   This document makes no request to IANA.

8.  Security Considerations

   This document is devoted to threat analysis of the Locator/Identifier
   Separation Protocol and is then a piece of choice to understand the
   security risks at stake while deploying LISP in non-trustable
   environment.

   The purpose of this document is not to provide recommendations to
   protect against attacks, however most of threats can be prevented
   with careful deployment and configuration (e.g., filter) and also by
   applying the general rules in security that consist in activating
   only features that are necessary in the deployment and verifying the
   validity of the information obtained from third parties.  More
   detailed recommendation are given in [book_chapter].

   The control-plane is probably the most critical part of LISP from a
   security viewpoint and it is worth to notice that the specifications
   already offer authentication mechanism for Map-Register messages
   ([RFC6833]) and that [I-D.ietf-lisp-sec] and [I-D.ietf-lisp-ddt] are
   clearly going in the direction of a secure control-plane.









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9.  Acknowledgments

   This document builds upon the draft of Marcelo Bagnulo
   ([I-D.bagnulo-lisp-threat]), where the flooding attack and the
   reference environment were first described.

   The authors would like to thank Ronald Bonica, Albert Cabellos, Noel
   Chiappa, Florin Coras, Vina Ermagan, Dino Farinacci, Stephen Farrell,
   Joel Halpern, Emily Hiltzik, Darrel Lewis, Edward Lopez, Fabio Maino,
   Terry Manderson, and Jeff Wheeler for their comments.

   This work has been partially supported by the INFSO-ICT-216372
   TRILOGY Project (www.trilogy-project.org).

10.  References

10.1.  Normative References

   [RFC6169]  Krishnan, S., Thaler, D., and J. Hoagland, "Security
              Concerns with IP Tunneling", RFC 6169, April 2011.

   [RFC6830]  Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
              Locator/ID Separation Protocol (LISP)", RFC 6830, January
              2013.

   [RFC6832]  Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
              "Interworking between Locator/ID Separation Protocol
              (LISP) and Non-LISP Sites", RFC 6832, January 2013.

   [RFC6833]  Fuller, V. and D. Farinacci, "Locator/ID Separation
              Protocol (LISP) Map-Server Interface", RFC 6833, January
              2013.

   [RFC6834]  Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID
              Separation Protocol (LISP) Map-Versioning", RFC 6834,
              January 2013.

   [RFC6836]  Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,
              "Locator/ID Separation Protocol Alternative Logical
              Topology (LISP+ALT)", RFC 6836, January 2013.

   [RFC6837]  Lear, E., "NERD: A Not-so-novel Endpoint ID (EID) to
              Routing Locator (RLOC) Database", RFC 6837, January 2013.

   [RFC6973]  Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
              Morris, J., Hansen, M., and R. Smith, "Privacy
              Considerations for Internet Protocols", RFC 6973, July
              2013.



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10.2.  Informative References

   [Chu]      Jerry Chu, H., "Tuning TCP Parameters for the 21st Century
              ", 75th IETF, Stockholm, July 2009,
              <http://tools.ietf.org/wg/savi/>.

   [I-D.bagnulo-lisp-threat]
              Bagnulo, M., "Preliminary LISP Threat Analysis", draft-
              bagnulo-lisp-threat-01 (work in progress), July 2007.

   [I-D.ietf-lisp-ddt]
              Fuller, V., Lewis, D., Ermagan, V., and A. Jain, "LISP
              Delegated Database Tree", draft-ietf-lisp-ddt-01 (work in
              progress), March 2013.

   [I-D.ietf-lisp-sec]
              Maino, F., Ermagan, V., Cabellos-Aparicio, A., Saucez, D.,
              and O. Bonaventure, "LISP-Security (LISP-SEC)", draft-
              ietf-lisp-sec-04 (work in progress), October 2012.

   [I-D.ietf-tcpm-tcp-security]
              Gont, F., "Survey of Security Hardening Methods for
              Transmission Control Protocol (TCP) Implementations",
              draft-ietf-tcpm-tcp-security-03 (work in progress), March
              2012.

   [I-D.meyer-lisp-cons]
              Brim, S., "LISP-CONS: A Content distribution Overlay
              Network Service for LISP", draft-meyer-lisp-cons-04 (work
              in progress), April 2008.

   [I-D.saucez-lisp-mapping-security]
              Saucez, D. and O. Bonaventure, "Securing LISP Mapping
              replies", draft-saucez-lisp-mapping-security-00 (work in
              progress), February 2011.

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, March 2004.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC5386]  Williams, N. and M. Richardson, "Better-Than-Nothing
              Security: An Unauthenticated Mode of IPsec", RFC 5386,
              November 2008.

   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, February 2012.



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   [SAVI]     IETF, "Source Address Validation Improvements Working
              Group ", 2013, <http://tools.ietf.org/wg/savi/>.

   [Saucez09]
              Saucez, D. and L. Iannone, "How to mitigate the effect of
              scans on mapping systems ", Trilogy Summer School on
              Future Internet, 2009.

   [book_chapter]
              Saucez, D., Iannone, L., and O. Bonaventure, "The Map-and-
              Encap Locator/Identifier separation paradigm: a Security
              Analysis ", Solutions for Sustaining Scalability in
              Internet Growth, IGI Global, 2013.

Appendix A.  Document Change Log

   o  Version 08 Posted October 2013.

      *  Addition of a privacy consideration note.

      *  Editorial changes

   o  Version 07 Posted October 2013.

      *  This version is updated according to the thorough review made
         during October 2013 LISP WG interim meeting.

      *  Brief recommendations put in the security consideration
         section.

      *  Editorial changes

   o  Version 06 Posted October 2013.

      *  Complete restructuration, temporary version to be used at
         October 2013 interim meeting.

   o  Version 05 Posted August 2013.

      *  Removal of severity levels to become a short recommendation to
         reduce the risk of the discussed threat.

   o  Version 04 Posted February 2013.

      *  Clear statement that the document compares threats of public
         LISP deployments with threats in the current Internet
         architecture.




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      *  Addition of a severity level discussion at the end of each
         section.

      *  Addressed comments from V. Ermagan and D. Lewis' reviews.

      *  Updated References.

      *  Further editorial polishing.

   o  Version 03 Posted October 2012.

      *  Dropped Reference to RFC 2119 notation because it is not
         actually used in the document.

      *  Deleted future plans section.

      *  Updated References

      *  Deleted/Modified sentences referring to the early status of the
         LISP WG and documents at the time of writing early versions of
         the document.

      *  Further editorial polishing.

      *  Fixed all ID nits.

   o  Version 02 Posted September 2012.

      *  Added a new attack that combines overclaiming and de-
         aggregation (see Section 4.4.2).

      *  Editorial polishing.

   o  Version 01 Posted February 2012.

      *  Added discussion on LISP-DDT.

   o  Version 00 Posted July 2011.

      *  Added discussion on LISP-MS>.

      *  Added discussion on Instance ID in Section 4.3.2.

      *  Editorial polishing of the whole document.

      *  Added "Change Log" appendix to keep track of main changes.

      *  Renamed "draft-saucez-lisp-security-03.txt.



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Authors' Addresses

   Damien Saucez
   INRIA
   2004 route des Lucioles BP 93
   06902 Sophia Antipolis Cedex
   France

   Email: damien.saucez@inria.fr


   Luigi Iannone
   Telecom ParisTech
   23, Avenue d'Italie, CS 51327
   75214 PARIS Cedex 13
   France

   Email: luigi.iannone@telecom-paristech.fr


   Olivier Bonaventure
   Universite catholique de Louvain
   Place St. Barbe 2
   Louvain la Neuve
   Belgium

   Email: olivier.bonaventure@uclouvain.be
























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