draft-ietf-manet-nhdp-sec-threats-06.txt   rfc7186.txt 
Mobile Ad hoc Networking (MANET) J. Yi Internet Engineering Task Force (IETF) J. Yi
Internet-Draft LIX, Ecole Polytechnique Request for Comments: 7186 LIX, Ecole Polytechnique
Intended status: Informational U. Herberg Category: Informational U. Herberg
Expires: December 19, 2013 Fujitsu Laboratories of America ISSN: 2070-1721 Fujitsu Laboratories of America
T. Clausen T. Clausen
LIX, Ecole Polytechnique LIX, Ecole Polytechnique
June 17, 2013 April 2014
Security Threats for NHDP Security Threats for the Neighborhood Discovery Protocol (NHDP)
draft-ietf-manet-nhdp-sec-threats-06
Abstract Abstract
This document analyzes common security threats of the Neighborhood This document analyzes common security threats of the Neighborhood
Discovery Protocol (NHDP), and describes their potential impacts on Discovery Protocol (NHDP) and describes their potential impacts on
MANET routing protocols using NHDP. This document is not intended to Mobile Ad Hoc Network (MANET) routing protocols using NHDP. This
propose solutions to the threats described. document is not intended to propose solutions to the threats
described.
Status of this Memo
This Internet-Draft is submitted in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is not an Internet Standards Track specification; it is
Task Force (IETF). Note that other groups may also distribute published for informational purposes.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
This Internet-Draft will expire on December 19, 2013. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7186.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. NHDP Threat Overview . . . . . . . . . . . . . . . . . . . . . 4 3. NHDP Threat Overview . . . . . . . . . . . . . . . . . . . . 4
4. Detailed Threat Description . . . . . . . . . . . . . . . . . 5 4. Detailed Threat Description . . . . . . . . . . . . . . . . . 5
4.1. Jamming . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Jamming . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Denial of Service Attack . . . . . . . . . . . . . . . . . 5 4.2. Denial-of-Service Attack . . . . . . . . . . . . . . . . 5
4.3. Eavesdropping and Traffic Analysis . . . . . . . . . . . . 6 4.3. Eavesdropping and Traffic Analysis . . . . . . . . . . . 6
4.4. Incorrect HELLO Message Generation . . . . . . . . . . . . 7 4.4. Incorrect HELLO Message Generation . . . . . . . . . . . 7
4.4.1. Identity Spoofing . . . . . . . . . . . . . . . . . . 7 4.4.1. Identity Spoofing . . . . . . . . . . . . . . . . . . 7
4.4.2. Link Spoofing . . . . . . . . . . . . . . . . . . . . 8 4.4.2. Link Spoofing . . . . . . . . . . . . . . . . . . . . 8
4.5. Replay Attack . . . . . . . . . . . . . . . . . . . . . . 9 4.5. Replay Attack . . . . . . . . . . . . . . . . . . . . . . 9
4.6. Message Timing Attacks . . . . . . . . . . . . . . . . . . 9 4.6. Message Timing Attacks . . . . . . . . . . . . . . . . . 9
4.6.1. Interval Time Attack . . . . . . . . . . . . . . . . . 9 4.6.1. Interval Time Attack . . . . . . . . . . . . . . . . 10
4.6.2. Validity Time Attack . . . . . . . . . . . . . . . . . 10 4.6.2. Validity Time Attack . . . . . . . . . . . . . . . . 10
4.7. Indirect Channel Overloading . . . . . . . . . . . . . . . 10 4.7. Indirect Channel Overloading . . . . . . . . . . . . . . 10
4.8. Attack on Link Quality Update . . . . . . . . . . . . . . 11 4.8. Attack on Link Quality Update . . . . . . . . . . . . . . 11
5. Impact of inconsistent Information Bases on Protocols 5. Impact of Inconsistent Information Bases on Protocols using
using NHDP . . . . . . . . . . . . . . . . . . . . . . . . . . 12 NHDP . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. MPR Calculation . . . . . . . . . . . . . . . . . . . . . 12 5.1. MPR Calculation . . . . . . . . . . . . . . . . . . . . . 12
5.1.1. Flooding Disruption due to Identity Spoofing . . . . . 12 5.1.1. Flooding Disruption due to Identity Spoofing . . . . 12
5.1.2. Flooding Disruption due to Link Spoofing . . . . . . . 13 5.1.2. Flooding Disruption due to Link Spoofing . . . . . . 13
5.1.3. Broadcast Storm . . . . . . . . . . . . . . . . . . . 14 5.1.3. Broadcast Storm . . . . . . . . . . . . . . . . . . . 14
5.2. Routing Loops . . . . . . . . . . . . . . . . . . . . . . 15 5.2. Routing Loops . . . . . . . . . . . . . . . . . . . . . . 15
5.3. Invalid or Non-Existing Paths to Destinations . . . . . . 15 5.3. Invalid or Nonexistent Paths to Destinations . . . . . . 16
5.4. Data Sinkhole . . . . . . . . . . . . . . . . . . . . . . 16 5.4. Data Sinkhole . . . . . . . . . . . . . . . . . . . . . . 16
6. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 16 6. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 9.1. Normative References . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
The Neighborhood Discovery Protocol (NHDP) [RFC6130] allows routers The Neighborhood Discovery Protocol (NHDP) [RFC6130] allows routers
to acquire topological information up to two hops away from to acquire topological information up to two hops away from
themselves, by way of periodic HELLO message exchanges. The themselves, by way of periodic HELLO message exchanges. The
information acquired by NHDP is used by other protocols, such as information acquired by NHDP is used by other protocols, such as the
OLSRv2 [I-D.ietf-manet-olsrv2] and SMF [RFC6621]. The topology Optimized Link State Routing Protocol version 2 (OLSRv2) [RFC7181]
and Simplified Multicast Forwarding (SMF) [RFC6621]. The topology
information, acquired by way of NHDP, serves these routing protocols information, acquired by way of NHDP, serves these routing protocols
by detecting and maintaining local 1-hop and 2-hop neighborhood by detecting and maintaining local 1-hop and 2-hop neighborhood
information. information.
As NHDP is typically used in wireless environments, it is potentially As NHDP is typically used in wireless environments, it is potentially
exposed to different kinds of security threats, some of which are of exposed to different kinds of security threats, some of which are of
particular significance as compared to wired networks. As radio particular significance as compared to wired networks. As radio
signals can be received as well as transmitted by any compatible signals can be received as well as transmitted by any compatible
wireless device within radio range, there is commonly no physical wireless device within radio range, there is commonly no physical
protection as otherwise known for wired networks. NHDP does not protection as otherwise known for wired networks. NHDP does not
define any explicit security measures for protecting the integrity of define any explicit security measures for protecting the integrity of
the information it acquires, however suggests that the integrity the information it acquires; however, it suggests that the integrity
protection be addressed in a fashion appropriate to the deployment of protection be addressed in a fashion appropriate to the deployment of
the network. the network.
This document is based on the assumption that no additional security This document is based on the assumption that no additional security
mechanism such as IPsec is used in the IP layer, as not all MANET mechanism such as IPsec is used in the IP layer, as not all MANET
deployments may be suitable to deploy common IP protection mechanisms deployments may be able to accommodate such common IP protection
(e.g., because of limited resources of MANET routers to support the mechanisms (e.g., because of limited resources of MANET routers).
IPsec stack). The document analyzes possible attacks on and mis- The document analyzes possible attacks on and misconfigurations of
configurations of NHDP and outlines the consequences of such attacks/ NHDP and outlines the consequences of such attacks/misconfigurations
mis-configurations to the state maintained by NHDP in each router to the state maintained by NHDP in each router (and, thus, made
(and, thus, made available to protocols using this state). available to protocols using this state).
This document is not intended to propose solutions to the threats This document is not intended to propose solutions to the threats
described. [I-D.ietf-manet-nhdp-olsrv2-sec] provides further described. [RFC7185] provides further information on how to enable
information on how to enable integrity protection to NHDP, which can integrity protection to NHDP, which can help mitigating the threats
help mitigating the threats described related to identity spoofing. described related to identity spoofing.
It should be noted that many NHDP implementations are configurable It should be noted that many NHDP implementations are configurable,
and so an attack on the configuration system (such as [RFC6779]) can and so an attack on the configuration system (such as [RFC6779]) can
be used to adversely affect the operation of an NHDP implementation. be used to adversely affect the operation of an NHDP implementation.
The NHDP MIB module [RFC6779] might help monitoring some of the The NHDP MIB module [RFC6779] might help monitoring some of the
security attacks mentioned in this document. Note that, security attacks mentioned in this document. [MGMT-SNAP] provides a
[I-D.nguyen-manet-management] contains specific guidelines on MANET snapshot of OLSRv2-routed MANET management as currently deployed,
network management, taking into account the specific nature of while [MANET-MGMT] is intended to provide specific guidelines on
MANETs. MANET network management considering the various MIB modules that
have been written.
2. Terminology 2. Terminology
This document uses the terminology and notation defined in [RFC5444], This document uses the terminology and notation defined in
NHDP [RFC6130] and [RFC4949]. "Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format"
[RFC5444], "Mobile Ad Hoc Network (MANET) Neighborhood Discovery
Protocol (NHDP)" [RFC6130], and "Internet Security Glossary, Version
2" [RFC4949].
Additionally, this document introduces the following terminology: Additionally, this document introduces the following terminology:
NHDP Router: A MANET router, running NHDP as specified in [RFC6130]. NHDP router: A MANET router, running NHDP as specified in [RFC6130].
Attacker: A device, present in the network and which intentionally Attacker: A device that is present in the network and intentionally
seeks to compromise the information bases in NHDP routers. seeks to compromise the information bases in NHDP routers.
Compromised NHDP Router: An attacker, present in the network and Compromised NHDP router: An attacker that is present in the network
which generates syntactically correct NHDP control messages. and generates syntactically correct NHDP control messages.
Control messages emitted by a Compromised NHDP router may contain Control messages emitted by a compromised NHDP router may contain
additional information, or omit information, as compared to a additional information, or omit information, as compared to a
control message generated by a non-compromized NHDP router located control message generated by a non-compromised NHDP router located
in the same topological position in the network. in the same topological position in the network.
Legitimate NHDP Router: An NHDP router, which is not a Compromised Legitimate NHDP router: An NHDP router that is not a compromised
NHDP Router. NHDP router.
3. NHDP Threat Overview 3. NHDP Threat Overview
NHDP defines a HELLO messages exchange, enabling each NHDP Router to NHDP defines a HELLO messages exchange, enabling each NHDP router to
acquire topological information describing its 1-hop and 2-hop acquire topological information describing its 1-hop and 2-hop
neighbors, and specifies information bases for recording this neighbors, and specifies information bases for recording this
information. information.
An NHDP Router periodically transmits HELLO messages using a link- An NHDP router periodically transmits HELLO messages using a link-
local multicast on each of its interfaces with a hop-limit of 1 local multicast on each of its interfaces with a hop-limit of 1
(i.e., HELLOs are never forwarded). In these HELLO messages, an NHDP (i.e., HELLOs are never forwarded). In these HELLO messages, an NHDP
Router announces the IP addresses as heard, symmetric or lost router announces the IP addresses as heard, symmetric, or lost
neighbor interface addresses. neighbor interface addresses.
An Attacker has several ways of harming this neighbor discovery An Attacker has several ways of harming this neighbor discovery
process: It can announce "wrong" information about its identity, process: it can announce "wrong" information about its identity,
postulate non-existent links, and replay HELLO messages. These postulate nonexistent links, and replay HELLO messages. These
attacks are presented in detail in Section 4. attacks are presented in detail in Section 4.
The different ways of attacking an NHDP deployment may eventually The different ways of attacking an NHDP deployment may eventually
lead to inconsistent information bases, not accurately reflecting the lead to inconsistent information bases, not accurately reflecting the
correct topology of the MANET. The consequence hereof is that correct topology of the MANET. The consequence is that protocols
protocols using NHDP will base their operation on incorrect using NHDP will base their operation on incorrect information,
information, causing routing protocols to not be able to calculate causing routing protocols to not be able to calculate correct (or
correct (or any) paths, degrade the performance of flooding any) paths, degrade the performance of flooding operations based on
operations based on reduced relay sets, etc. These consequences to reduced relay sets, etc. These consequences to protocols using NHDP
protocols using NHDP are described in detail in Section 5. are described in detail in Section 5.
4. Detailed Threat Description 4. Detailed Threat Description
For each threat, described in the below, a description of the For each threat, a description of the mechanism of the corresponding
mechanism of the corresponding attack is given, followed by a attack is given, followed by a description of how the attack affects
description of how the attack affects NHDP. The impacts from each NHDP. The impacts from each attack on protocols using NHDP are given
attack on protocols using NHDP are given in Section 5. in Section 5.
For simplicity in the description, examples given assume that NHDP For simplicity in the description, the examples given assume that
Routers have a single interface with a single IP address configured. NHDP routers have a single interface with a single IP address
All the attacks apply, however, for NHDP Routers with multiple configured. All the attacks apply, however, for NHDP routers with
interfaces and multiple addresses as well. multiple interfaces and multiple addresses as well.
4.1. Jamming 4.1. Jamming
One vulnerability, common for all protocols operating a wireless ad One vulnerability, common for all protocols operating a wireless ad
hoc network, is that of "jamming", i.e., that a device generates hoc network, is that of "jamming", i.e., that a device generates
massive amounts of interfering radio transmissions, which will massive amounts of interfering radio transmissions, which will
prevent legitimate traffic (e.g.,control traffic as well as data prevent legitimate traffic (e.g., control traffic as well as data
traffic) on part of a network. Jamming is a form of Interference and traffic) on part of a network. Jamming is a form of interference and
Overload with threat consequences of Disruption [RFC4593]. overload with the threat consequence of disruption [RFC4593].
Depending on lower layers, this may not affect transmissions: HELLO Depending on lower layers, this may not affect transmissions: HELLO
messages from an NHDP Router with "jammed" interfaces may be received messages from an NHDP router with "jammed" interfaces may be received
by other NHDP Routers. As NHDP identifies whether a link to a by other NHDP routers. As NHDP identifies whether a link to a
neighbor is uni-directional or bi-directional, a routing protocol neighbor is unidirectional or bidirectional, a routing protocol that
that uses NHDP for neighborhood discovery may ignore a link from a uses NHDP for neighborhood discovery may ignore a link from a jammed
jammed NHDP Router to a non-jammed NHDP Router. The jammed router (a NHDP router to a non-jammed NHDP router. The jammed router (a router
router with jammed carrier) would appear simply as "disconnected" for with jammed carrier) would appear simply as "disconnected" for the
the un-jammed part of the network - which is able to maintain unjammed part of the network, which is able to maintain accurate
accurate topology maps. topology maps.
If, due to a jamming attack, a considerable amount of HELLO messages If a considerable amount of HELLO messages are lost or corrupted due
are lost or corrupted due to collisions, neighbor NHDP Routers are to collisions caused by a jamming attack, neighbor NHDP routers are
not able to establish links between themselves any more. Thus, NHDP not able to establish links between themselves any more. Thus, NHDP
will present empty information bases to the protocols using it. will present empty information bases to the protocols using it.
4.2. Denial of Service Attack 4.2. Denial-of-Service Attack
A Denial of Service (DoS) attack can be a result of misconfiguration A denial-of-service (DoS) attack can be a result of misconfiguration
of Legitimate NHDP Routers (e.g., very short HELLO transmission of legitimate NHDP routers (e.g., very short HELLO transmission
interval) or malicious behavior of Compromised NHDP Routers interval) or malicious behavior of compromised NHDP routers
[ACCT2012], so called byzantine routers [RFC4593]. DoS is a form of [ACCT2012], so-called Byzantine routers [RFC4593]. DoS is a form of
Interference and Overload with threat consequences of Disruption interference and overload with the threat consequence of disruption
[RFC4593]. [RFC4593].
By transmitting a huge amount of HELLO messages in a short period of By transmitting a huge amount of HELLO messages in a short period of
time, NHDP Routers can increase channel occupation as introduced in time, NHDP routers can increase channel occupation as described in
Section 4.1. Furthermore, a Compromised NHDP Router can spoof a Section 4.1. Furthermore, a compromised NHDP router can spoof a
large amount of different IP addresses, and send HELLOs to its large amount of different IP addresses and send HELLOs to its
neighbors to fill their Link/Neighbor Sets. This may result in neighbors to fill their Link/Neighbor Sets. This may result in
memory overflow, and makes the processing of legitimate HELLO memory overflow, and it makes the processing of legitimate HELLO
messages impossible. A Compromised NHDP Router can also use link messages impossible. A compromised NHDP router can also use link
spoofing in its HELLO messages, generating huge 2-hop Sets in spoofing in its HELLO messages, generating huge 2-hop Sets in
adjacent NHDP Routers and therefore potentially a memory overflow. adjacent NHDP routers and therefore potentially a memory overflow.
Moreover, protocols such as SMF and OLSRv2, using the 2-hop Moreover, protocols such as SMF and OLSRv2, using the 2-hop
information for MPR calculation, may exhaust the available information for multipoint relay (MPR) calculation, may exhaust the
computational resources of the router if the Neighbor Set and 2-hop available computational resources of the router if the Neighbor Set
Sets have too many entries. and 2-hop Sets have too many entries.
By exhausting the memory, CPU, or (and) channel resources of a router By exhausting the memory, CPU, and/or channel resources of a router
in a DoS attack or a misconfiguration, NHDP Routers may not be able in a DoS attack or a misconfiguration, NHDP routers may not be able
to accomplish their specified tasks of exchanging 1-hop and 2-hop to accomplish their specified tasks of exchanging 1-hop and 2-hop
neighborhood information, and thereby disturbing the operation of neighborhood information, and thereby disturbing the operation of
routing protocols using NHDP. routing protocols using NHDP.
In some MANETs, the routers are powered by battery. Another In some MANETs, the routers are powered by battery. Another
consequence of DoS attack in such networks is that the power will be consequence of a DoS attack in such networks is that the power will
drained quickly by unnecessary message processing, transmission and be drained quickly by unnecessary processing, transmitting, and
receiving. receiving of messages.
4.3. Eavesdropping and Traffic Analysis 4.3. Eavesdropping and Traffic Analysis
Eavesdropping, sometimes referred as sniffing, is a common and easy Eavesdropping, sometimes referred to as sniffing, is a common and
passive attack in a wireless environment. Once a packet is easy passive attack in a wireless environment. Once a packet is
transmitted, any adjacent NHDP Router can potentially obtain a copy, transmitted, any adjacent NHDP router can potentially obtain a copy,
for immediate or later processing. Neither the source nor the for immediate or later processing. Neither the source nor the
intended destination can detect this. A malicious NHDP Router can intended destination can detect this. A malicious NHDP router can
eavesdrop on the NHDP message exchange and thus learn the local eavesdrop on the NHDP message exchange and thus learn the local
topology. It may also eavesdrop on data traffic to learn source and topology. It may also eavesdrop on data traffic to learn source and
destination addresses of data packets, or other header information, destination addresses of data packets, or other header information,
as well as the packet payload. as well as the packet payload.
Eavesdropping does not pose a direct threat to the network nor to Eavesdropping does not pose a direct threat to the network or to
NHDP, in as much as that it does not alter the information recorded NHDP, in as much as that it does not alter the information recorded
by NHDP in its information bases and presented to other protocols by NHDP in its information bases and presented to other protocols.
using it, but it can provide network information required for However, eavesdropping can provide network information required for
enabling other attacks, such as the identity of communicating NHDP enabling other attacks, such as the identity of communicating NHDP
Routers, detection of link characteristic, and NHDP Router routers, detection of link characteristics, and NHDP router
configuration. The compromised NHDP Routers may use the obtained configuration. The compromised NHDP routers may use the obtained
information to launch subsequent attacks, and they may also share information to launch subsequent attacks, and they may also share
NHDP routing information with other NHDP or non-NHDP entities. NHDP routing information with other NHDP or non-NHDP entities.
[RFC4593] would categorize the threat consequence as Disclosure. [RFC4593] would categorize the threat consequence as disclosure.
Traffic analysis normally comes along with eavesdropping, which is Traffic analysis normally follows eavesdropping, which is the process
the process of intercepting messages in order to deduce information of intercepting messages in order to deduce information from
from communication patterns. It can be performed even HELLO messages communication patterns. It can be performed even when HELLO messages
are encrypted (encryption is not a part of NHDP), for example: are encrypted (encryption is not a part of NHDP), for example:
o Triggered HELLO messages: an attacker could figure out that o Triggered HELLO messages: an attacker could figure out that
messages are triggered and determine that there was a change of messages are triggered and determine that there was a change of
symmetric neighbors of an NHDP Router sending the HELLO (as well symmetric neighbors of an NHDP router sending the HELLO (as well
get the frequency). get the frequency).
o Message size: the message grows exactly by x bytes per neighbor. o Message size: the message grows exactly by x bytes per neighbor.
Depending on which cipher is used for the encryption, some Depending on which cipher is used for the encryption, some
information about the size could be inferred and thus the number information about the size could be inferred, and thus the number
of neighbors guessed. of neighbors could be guessed.
[RFC4593] would categorize the threat consequence as Disclosure. [RFC4593] would categorize the threat consequence as disclosure.
4.4. Incorrect HELLO Message Generation 4.4. Incorrect HELLO Message Generation
An NHDP Router performs two distinct tasks: it periodically generates An NHDP router performs two distinct tasks: it periodically generates
HELLO messages, and it processes incoming HELLO messages from HELLO messages, and it processes incoming HELLO messages from
neighbor NHDP Routers. This section describes security attacks neighbor NHDP routers. This section describes security attacks
involving the HELLO generation. involving the HELLO generation.
4.4.1. Identity Spoofing 4.4.1. Identity Spoofing
Identity spoofing implies that a Compromised NHDP Router sends HELLO Identity spoofing implies that a compromised NHDP router sends HELLO
messages, pretending to have the identity of another NHDP Router, or messages, pretending to have the identity of another NHDP router, or
even a router that does not exist in the networks. A Compromised even a router that does not exist in the networks. A compromised
NHDP Router can accomplish this by using another IP address in an NHDP router can accomplish this by using an IP address, which is not
address block of a HELLO message, and associating this address with a its own, in an address block of a HELLO message, and associating this
LOCAL_IF Address Block TLV [IJNSIA2010]. address with a LOCAL_IF Address Block TLV [IJNSIA2010].
An NHDP Router receiving the HELLO message from a neighbor, will An NHDP router receiving that HELLO message from a neighbor will
assume that it originated from the NHDP Router with the spoofed assume that it originated from the NHDP router with the spoofed
interface address. As a consequence, it will add a Link Tuple to interface address. As a consequence, it will add a Link Tuple to
that neighbor with the spoofed address, and include it in its next that neighbor with the spoofed address, and include it in its next
HELLO messages as a heard neighbor (and possibly as symmetric HELLO messages as a heard neighbor (and possibly as a symmetric
neighbor after another HELLO exchange). neighbor after another HELLO exchange).
Identity spoofing is particular harmful if a Compromised NHDP Router Identity spoofing is particularly harmful if a compromised NHDP
spoofs the identity of another NHDP Router that exists in the same router spoofs the identity of another NHDP router that exists in the
routing domain. With respect to NHDP, such a duplicated, spoofed same routing domain. With respect to NHDP, such a duplicated,
address can lead to an inconsistent state up to two hops from an NHDP spoofed address can lead to an inconsistent state up to two hops from
Router. [RFC4593] would categorize the threat consequence as an NHDP router. [RFC4593] would categorize the threat consequences
Disclosure and Deception. as disclosure and deception.
Figure 1 depicts a simple example. In that example, NHDP Router A is Figure 1 depicts a simple example. In that example, NHDP router A is
in radio range of C, but not of the Compromised NHDP Router X. If X in radio range of NHDP router C, but not of the compromised NHDP
spoofs the address of A, that can lead to conflicts for routing router X. If X spoofs the address of A, that can lead to conflicts
protocol that uses NHDP, and therefore for wrong path calculations as for a routing protocol that uses NHDP, and therefore for wrong path
well as incorrect data traffic forwarding. calculations as well as incorrect data traffic forwarding.
.---. .---. .---. .---. .---. .---.
| A |----| C |----| X | | A |----| C |----| X |
'---' '---' '---' '---' '---' '---'
Figure 1 Figure 1
Figure 2 depicts another example. In this example, A is two hops Figure 2 depicts another example. In this example, NHDP router A is
away from NHDP Router C, reachable through NHDP Router B. If the two hops away from NHDP router C, reachable through NHDP router B.
Compromised NHDP Router X spoofs the address of A, D will take A as If the compromised NHDP router X spoofs the address of A, NHDP router
its one hop neighbor, and C may think that A is indeed reachable D will take A as its 1-hop neighbor, and C may think that A is indeed
through NHDP Router D. reachable through D.
.---. .---. .---. .---. .---. .---. .---. .---. .---. .---.
| A |----| B |----| C |----| D |----| X | | A |----| B |----| C |----| D |----| X |
'---' '---' '---' '---' '---' '---' '---' '---' '---' '---'
Figure 2 Figure 2
4.4.2. Link Spoofing 4.4.2. Link Spoofing
Similar to identity spoofing, link spoofing implies that a Similar to identity spoofing, link spoofing implies that a
Compromised NHDP Router sends HELLO messages, signaling an incorrect compromised NHDP router sends HELLO messages, signaling an incorrect
set of neighbors, sometimes referred to as Falsification [RFC4593]. set of neighbors. This is sometimes referred to as falsification
This may take either of two forms: [RFC4593], and in NHDP it may take either of two forms:
o A Compromised NHDP Router can postulate addresses of non-present o A compromised NHDP router can postulate addresses of non-present
neighbor NHDP Routers in an address block of a HELLO, associated neighbor NHDP routers in an address block of a HELLO, associated
with LINK_STATUS TLVs. with LINK_STATUS TLVs.
o A Compromised NHDP Router can "ignore" otherwise existing o A compromised NHDP router can "ignore" otherwise existing
neighbors by not advertising them in its HELLO messages. neighbors by not advertising them in its HELLO messages.
The effect of link spoofing with respect to NHDP are twofold, The effect of link spoofing with respect to NHDP are twofold,
depending on the two cases mentioned above: If the Compromised NHDP depending on the two cases mentioned above:
Router ignores existing neighbors in its advertisements, links will
be missing in the information bases maintained by other routers, and o If the compromised NHDP router ignores existing neighbors in its
there may not be any connectivity to or from these NHDP Routers to advertisements, links will be missing in the information bases
others NHDP Routers in the MANET. If, on the other hand, the maintained by other routers, and there may not be any connectivity
Compromised NHDP Router advertises non-existing links, this will lead for these NHDP routers to or from other NHDP routers in the MANET.
to inclusion of topological information in the information base,
describing non-existing links in the network (which, then, may be o On the other hand, if the compromised NHDP router advertises
used by other protocols using NHDP in place of other, existing, nonexistent links, this will lead to inclusion of topological
links). [RFC4593] would categorize the threat consequence as information in the information base, describing nonexistent links
Usurpation, Deception and Disruption. in the network (which, then, may be used by other protocols using
NHDP in place of other, existing, links).
[RFC4593] would categorize the threat consequences as usurpation,
deception, and disruption.
4.5. Replay Attack 4.5. Replay Attack
A replay attack implies that control traffic from one region of the A replay attack implies that control traffic from one region of the
network is recorded and replayed in a different region at (almost) network is recorded and replayed in a different region at (almost)
the same time, or in the same region at a different time. This may, the same time, or in the same region at a different time. This may,
for example, happen when two Compromised NHDP Routers collaborate on for example, happen when two compromised NHDP routers collaborate on
an attack, one recording traffic in its proximity and tunneling it to an attack, one recording traffic in its proximity and tunneling it to
the other Compromised NHDP Router, which replays the traffic. In a the other compromised NHDP router, which replays the traffic. In a
protocol where links are discovered by testing reception, this will protocol where links are discovered by testing reception, this will
result in extraneous link creation (basically, a "virtual" link result in extraneous link creation (basically, a "virtual" link
between the two Compromised NHDP Routers will appear in the between the two compromised NHDP routers will appear in the
information bases of neighboring NHDP Routers). [RFC4593] would information bases of neighboring NHDP routers). [RFC4593] would
categorize this as a Falsification and Interference threat with a categorize this as a falsification and interference threat with
threat consequence of Usurpation, Deception, and Disruption. threat consequences of usurpation, deception, and disruption.
While this situation may result from an attack, it may also be While this situation may result from an attack, it may also be
intentional: if data-traffic also is relayed over the "virtual" link, intentional: if data traffic is also relayed over the "virtual" link,
the link being detected is indeed valid for use. This is, for the link being detected is indeed valid for use. This is, for
instance, used in wireless repeaters. If data traffic is not carried instance, used in wireless repeaters. If data traffic is not carried
over the virtual link, an imaginary, useless, link between the two over the virtual link, an imaginary, useless link between the two
Compromised NHDP Routers, has been advertised, and is being recorded compromised NHDP routers has been advertised and is being recorded in
in the information bases of their neighboring NHDP Routers. the information bases of their neighboring NHDP routers.
Compared to Incorrect HELLO Message attacks described in Section 4.4, Compared to incorrect HELLO message attacks described in Section 4.4,
the messages used in Replay attack are legitimate messages sent out the messages used in replay attacks are legitimate messages sent out
by (non-malicious) NHDP Routers and replayed at a later time or by (non-malicious) NHDP routers and replayed at a later time or
different locality by malicious routers. This makes this kind of different locality by malicious routers. This makes this kind of
attack harder to be detect and to counteract: integrity checks cannot attack harder to be detect and to counteract; integrity checks cannot
help in this case as the original message ICV (Integrity Check help in this case, as the original message's Integrity Check Value
Values) was correctly calculated. (ICV) was correctly calculated.
4.6. Message Timing Attacks 4.6. Message Timing Attacks
In NHDP, each HELLO message contains a "validity time" and may In NHDP, each HELLO message contains a "validity time" (the amount of
contain an "interval time" field, identifying the time for which time that information in that control message should be considered
information in that control message should be considered valid until valid before being discarded) and may contain an "interval time"
discarded, and the time until the next control message of the same field (the amount of time until the next control message of the same
type should be expected [RFC5497]. type should be expected) [RFC5497].
4.6.1. Interval Time Attack 4.6.1. Interval Time Attack
A use of the expected interval between two successive HELLO messages A use of the expected interval between two successive HELLO messages
is for determining the link quality in NHDP: if messages are not is for determining the link quality in NHDP: if messages are not
received within the expected intervals (e.g., a certain fraction of received within the expected intervals (e.g., a certain fraction of
messages are missing), then this may be used to exclude a link from messages are missing), then this may be used to exclude a link from
being considered as useful, even if (some) bi-directional being considered as useful, even if (some) bidirectional
communication has been verified. If a Compromised NHDP Router X communication has been verified. If a compromised NHDP router X
spoofs the identity of an existing NHDP Router A, and sends HELLOs spoofs the identity of an existing NHDP router A and sends HELLOs
indicating a low interval time, an NHDP Router B receiving this HELLO indicating a low interval time, an NHDP router B receiving this HELLO
will expect the following HELLO to arrive within the interval time will expect the following HELLO to arrive within the interval time
indicated - or otherwise, decrease the link quality for the link A-B. indicated. If that expectation is not met, the link quality for the
Thus, X may cause NHDP Router B's estimate of the link quality for link A-B will be decreased. Thus, X may cause NHDP router B's
the link A-B to fall below the limit, where it is no longer estimate of the link quality for the link A-B to fall below the
considered as useful and, thus, not used [CPSCOM2011]. [RFC4593] minimum considered useful, so the link would not be used
would categorize the threat consequence as Usurpation. [CPSCOM2011]. [RFC4593] would categorize the threat consequence as
usurpation.
4.6.2. Validity Time Attack 4.6.2. Validity Time Attack
A Compromised NHDP Router X can spoof the identity of an NHDP Router A compromised NHDP router X can spoof the identity of an NHDP router
A and send a HELLO using a low validity time (e.g.,1 ms). A A and send a HELLO using a low validity time (e.g., 1 ms). A
receiving NHDP Router B will discard the information upon expiration receiving NHDP router B will discard the information upon expiration
of that interval, i.e., a link between NHDP Router A and B will be of that interval, i.e., a link between NHDP router A and B will be
"torn down" by X. It can be caused by intended malicious behaviors, "torn down" by X. The sending of a low validity time can be caused
or simply mis-configuration in the NHDP Routers. [RFC4593] would by intended malicious behaviors or simply misconfiguration in the
categorize the threat consequence as Usurpation. NHDP routers. [RFC4593] would categorize the threat consequence as
usurpation.
4.7. Indirect Channel Overloading 4.7. Indirect Channel Overloading
Indirect Channel Overloading is when a Compromised NHDP Router X by Indirect Channel Overloading is when a compromised NHDP router X by
its actions causes other legitimate NHDP Routers to generate its actions causes other legitimate NHDP routers to generate
inordinate amounts of control traffic. This increases channel inordinate amounts of control traffic. This increases channel
occupation, and the overhead in each receiving NHDP Router processing occupation and the overhead in each receiving NHDP router that
this control traffic. With this traffic originating from Legitimate processes this control traffic. With this traffic originating from
NHDP Routers, the malicious device may remain undetected to the wider legitimate NHDP routers, the malicious device may remain undetected
network. It is a form of Interference and Overload with threat in the wider network. It is a form of interference and overload with
consequences of Disruption [RFC4593]. the threat consequence of disruption [RFC4593].
Figure 3 illustrates Indirect Channel Overloading with NHDP. A Figure 3 illustrates Indirect Channel Overloading with NHDP. A
Compromised NHDP Router X advertises a symmetric spoofed link to the compromised NHDP router X advertises a symmetric spoofed link to the
non-existing NHDP Router B (at time t0). Router A selects X as MPR nonexistent NHDP router B (at time t0). Router A selects X as MPR
upon reception of the HELLO, and will trigger a HELLO at t1. upon reception of the HELLO then triggers a HELLO at t1. Overhearing
Overhearing this triggered HELLO, the attacker sends another HELLO at this triggered HELLO, the attacker sends another HELLO at t2,
t2, advertising the link to B as lost, which leads to NHDP Router A advertising the link to B as lost; this causes NHDP router A to
deselecting the attacker as MPR, and another triggered message at t3. deselect the attacker as MPR, and to send another triggered message
The cycle may be repeated, alternating advertising the link X-B as at t3. The cycle may be repeated, where the link X-B is advertised
LOST and SYM. alternately as LOST and SYM.
MPRs(X) MPRs() MPRs(X) MPRs()
.---. .---. .---. .---. .---. .---. .---. .---.
| A | | A | | A | | A | | A | | A | | A | | A |
'---' '---' '---' '---' '---' '---' '---' '---'
| | | | | | | |
| SYM(B) | | LOST(B) | | SYM(B) | | LOST(B) |
| | | | | | | |
.---. .---. .---. .---. .---. .---. .---. .---.
| X | | X | | X | | X | | X | | X | | X | | X |
'---' '---' '---' '---' '---' '---' '---' '---'
. . . .
. . . .
. . . .
..... ..... ..... .....
. B . . B . . B . . B .
..... ..... ..... .....
t0 t1 t2 t3 t0 t1 t2 t3
Figure 3 Figure 3
4.8. Attack on Link Quality Update 4.8. Attack on Link Quality Update
According to NHDP, "Link quality is a mechanism whereby a router MAY According to NHDP [RFC6130]:
take considerations other than message exchange into account for
determining when a link is and is not a candidate for being Link quality is a mechanism whereby a router MAY take
considered as HEARD or SYMMETRIC. As such, it is a link admission considerations other than message exchange into account for
mechanism.". determining when a link is and is not a candidate for being
considered as HEARD or SYMMETRIC. As such, it is a "link
admission" mechanism.
Section 14.4 of NHDP [RFC6130] then lists several examples of which Section 14.4 of NHDP [RFC6130] then lists several examples of which
information can be used to update link quality. One of the listed information can be used to update link quality. One of the listed
examples is to update link quality based on [RFC5444] packet examples uses packet exchanges between neighbor routers (as described
exchanges between neighbor routers, e.g., an NHDP Router may update in [RFC5444]), e.g., an NHDP router may update the link quality of a
the link quality of a neighbor based on receipt or loss of packets if neighbor based on receipt or loss of packets if they include a
they include a sequential packet sequence number. sequential packet sequence number.
NHDP does not specify how to acquire link quality updates NHDP does not specify how to acquire link quality updates
normatively, however, attack vectors may be introduced if an normatively; however, attack vectors may be introduced if an
implementation chooses to calculate link quality based on packet implementation chooses to calculate link quality based on packet
sequence numbers. The consequences of such threats would depend on sequence numbers. The consequences of such threats would depend on
specific implementations. For example, if the link quality update is specific implementations. For example, if the link quality update is
based on sequential packet sequence number from neighbor routers, a based on a sequential packet sequence number from neighbor routers, a
Comprised NDHP Router can spoof packets appearing to be from another compromised NHDP router can spoof packets appearing to be from
Legitimate NHDP Router that skips some packet sequence numbers. The another legitimate NHDP router that skips some packet sequence
NHDP Router receiving the spoofed packets may degrade the link numbers. The NHDP router receiving the spoofed packets may degrade
quality as it appears that several packets have been dropped. the link quality as it appears that several packets have been
Eventually, the router remove the neighbor when the link quality dropped. Eventually, the router may remove the neighbor when the
drops below HYST_REJECT. link quality drops below HYST_REJECT.
5. Impact of inconsistent Information Bases on Protocols using NHDP 5. Impact of Inconsistent Information Bases on Protocols using NHDP
This section describes the impact on protocols, using NHDP, of NHDP This section describes the impact on protocols that use NHDP when
failing to obtain and represent accurate information, possibly as a NHDP fails to obtain and represent accurate information, possibly as
consequence of the attacks described in Section 4. This description a consequence of the attacks described in Section 4. This
emphasizes the impacts on the MANET protocols OLSRv2 description emphasizes the impacts on the MANET protocols OLSRv2
[I-D.ietf-manet-olsrv2], and SMF [RFC6621]. [RFC7181] and SMF [RFC6621].
5.1. MPR Calculation 5.1. MPR Calculation
MPR selection (as used in e.g., [I-D.ietf-manet-olsrv2] and MPR selection (as used in [RFC7181] and [RFC6621], for example) uses
[RFC6621]) uses information about a router's 1-hop and 2-hop information about a router's 1-hop and 2-hop neighborhood, assuming
neighborhood, assuming that (i) this information is accurate, and that (i) this information is accurate, and (ii) each 1-hop neighbor
(ii) all 1-hop neighbors are apt to act as as MPR, depending on the is apt to act as MPR, depending on the willingness it reports. Thus,
willingness they report. Thus, a Compromised NHDP router may seek to a compromised NHDP router may seek to manipulate the 1-hop and 2-hop
manipulate the 1-hop and 2-hop neighborhood information in a router neighborhood information in a router so as to cause the MPR selection
such as to cause the MPR selection to fail, leading to a flooding to fail, leading to a flooding disruption of traffic control
disruption of TC messages, which can result in incomplete topology messages. This can result in incomplete topology advertisement or
advertisement, or degrade the optimized flooding to classical can degrade the optimized flooding to classical flooding.
flooding.
5.1.1. Flooding Disruption due to Identity Spoofing 5.1.1. Flooding Disruption due to Identity Spoofing
A Compromised NHDP router can spoof the identify of other routers, to A compromised NHDP router can spoof the identify of other routers in
disrupt the MPR selection, so as to cache certain parts of the order to disrupt the MPR selection, so as to prevent certain parts of
network from the flooding traffic [IJNSIA2010]. the network from receiving flooded traffic [IJNSIA2010].
In Figure 4, a Compromised NHDP router X spoofs the identity of B. In Figure 4, a compromised NHDP router X spoofs the identity of B.
The link between X and C is correctly detected and listed in X's The link between X and C is correctly detected and listed in X's
HELLOs. Router A will receive HELLOs indicating links from, HELLOs. Router A will receive HELLOs indicating links from B:{B-E},
respectively B:{B-E}, X:{X-C, X-E}, and D:{D-E, D-C}. For router A, X:{X-C, X-E}, and D:{D-E, D-C}, respectively. For router A, X and D
X and D are equal candidates for MPR selection. To make sure the X are equal candidates for MPR selection. To make sure the X can be
can be selected as MPR for router A, X can set its willingness to the selected as MPR for router A, X can set its willingness to the
maximum value. maximum value.
.---. .---. .---. .---. .---. .---.
| E |----| D |----| C | | E |----| D |----| C |
'---' '---' '---' '---' '---' '---'
| | . | | .
| | . | | .
.---. .---. .---. .---. .---. .---.
| B |----| A |----| X | | B |----| A |----| X |
'---' '---' '---' '---' '---' '---'
spoofs B spoofs B
Figure 4 Figure 4
If B and X (i) accept MPR selection and (ii) forward flooded traffic If B and X (i) accept MPR selection and (ii) forward flooded traffic
as-if they were both B, identity spoofing by X is harmless. However, as if they were both B, identity spoofing by X is harmless. However,
if X does not forward flooded traffic (i.e., does not accept MPR if X does not forward flooded traffic (i.e., does not accept MPR
selection), its presence entails flooding disruption: selecting B selection), its presence entails flooding disruption: selecting B
over D renders C unreachable by flooded traffic. over D renders C unreachable by flooded traffic.
.---. .---.
| D | | D |
'---' '---'
| |
| |
.---. .---. .---. .---. .---. .---. .---. .---. .---. .---.
| X |----| A |----| B |----| C |----| E |... | X |----| A |----| B |----| C |----| E |...
'---' '---' '---' '---' '---' '---' '---' '---' '---' '---'
spoofs E spoofs E
Figure 5 Figure 5
In Figure 5, the Compromised NHDP router X spoofs the identity of E, In Figure 5, the compromised NHDP router X spoofs the identity of E,
i.e.,router A and C both receive HELLOs from a router identifying as i.e., routers A and C both receive HELLOs from a router identifying
E. For router B, A and C present the same neighbor sets, and are itself as E. For router B, routers A and C present the same neighbor
equal candidates for MPR selection. If router B selects only router sets and are equal candidates for MPR selection. If router B selects
A as MPR, C will not relay flooded traffic from or transiting via B, only router A as MPR, C will not relay flooded traffic from B or
and router X (and routers to the "right" of it) will not receive transiting via B, and router X (and routers to the "right" of it)
flooded traffic. will not receive flooded traffic.
5.1.2. Flooding Disruption due to Link Spoofing 5.1.2. Flooding Disruption due to Link Spoofing
A Compromised NHDP router can also spoof links to other NHDP routers, A compromised NHDP router can also spoof links to other NHDP routers,
and thereby makes itself appear as the most appealing candidate of thereby making itself appear as the most appealing candidate to be
MPR for its neighbors, possibly to the exclusion of other NHDP MPR for its neighbors, possibly to the exclusion of other NHDP
routers in the neighborhood (this, in particular, if the Compromised routers in the neighborhood. (In particular, this can occur if the
NHDP router spoof links to all other NHDP routers in the compromised NHDP router spoofs links to all other NHDP routers in the
neighborhood, plus to one other NHDP router). By thus excluding neighborhood, plus to one NHDP router outside the neighborhood.) By
other legitimate NHDP routers from being selected as MPR, the thus excluding other legitimate NHDP routers from being selected as
Compromised NHDP router will receive and be expected to relay all MPR, the compromised NHDP router will receive and be expected to
flooded traffic (e.g., TC messages in OLSRv2 or data traffic in SMF) relay all flooded traffic (e.g., traffic control messages in OLSRv2
- which it can then drop or otherwise manipulate. or data traffic in SMF) that it can then drop or otherwise
manipulate.
In the network in Figure 6, the Compromised NHDP router X spoofs In the network in Figure 6, the compromised NHDP router X spoofs
links to the existing router C, as well as to a fictitious W. Router links to the existing router C, as well as to a fictitious W. Router
A receives HELLOs from X and B, reporting X: {X-C, X-W}, b: {B-C}. A receives HELLOs from X and B, reporting X: {X-C, X-W}, B: {B-C}.
All else being equal, X appears a better choice as MPR than B, as X All else being equal, X appears a better choice for MPR than B, as X
appears to cover all neighbors of B, plus W. appears to cover all neighbors of B, plus W.
,---. ..... ,---. .....
| S | . C . | S | . C .
'---' ..... '---' .....
| . | .
| . | .
.---. .---. .---. .---. .---. .---. .---. .---. .---. .---.
| D |----| C |----| B |----| A |----| X | | D |----| C |----| B |----| A |----| X |
'---' '---' '---' '---' '---' '---' '---' '---' '---' '---'
. .
. .
..... .....
. w . . W .
..... .....
Figure 6 Figure 6
As router A will not select B as MPR, B will not relay flooded As router A will not select B as MPR, B will not relay flooded
messages received from router A. The NHDP routers on the left of B messages received from router A. The NHDP routers on the left of B
(starting with C) will, thus, not receive any flooded messages from (starting with C) will, thus, not receive any flooded messages from
or transiting NHDP router A (e.g., a message originating from S). router A or transiting router A (e.g., a message originating from S).
5.1.3. Broadcast Storm 5.1.3. Broadcast Storm
Compromised NHDP router may attack the network by attempting to A compromised NHDP router may attack the network by attempting to
degrade the performance of optimized flooding algorithms so as to be degrade the performance of optimized flooding algorithms so as to be
equivalent to classic flooding. This can be achieved by forcing an equivalent to classic flooding. This can be achieved by forcing an
NHDP router into choosing all its 1-hop neighbors as MPRs. In NHDP router into choosing all its 1-hop neighbors as MPRs. In
MANETs, a broadcast storm caused by classic flooding is a serious MANETs, a broadcast storm caused by classic flooding is a serious
problem which can result in redundancy, contention and collisions problem that can result in redundancy, contention, and collisions
[MOBICOM99]. [MOBICOM99].
As shown in Figure 7, the Compromised NHDP router X spoofs the As shown in Figure 7, the compromised NHDP router X spoofs the
identity of NHDP router B and, spoofs a link to router Y {B-Y} (Y identity of NHDP router B and, spoofs a link to router Y {B-Y} (Y
does not have to be exist). By doing so, the legitimate NHDP router does not have to exist). By doing so, the legitimate NHDP router A
A has to select the legitimate NHDP router B as its MPR, in order for has to select the legitimate NHDP router B as its MPR in order for it
it to reach all its 2-hop neighbors. The Compromised NHDP router Y to reach all its 2-hop neighbors. The compromised NHDP router Y can
can perform this identity+link spoofing for all of NHDP router A's perform this identity-and-link spoofing for all of NHDP router A's
1-hop neighbors, thereby forcing NHDP router A to select all its 1-hop neighbors, thereby forcing NHDP router A to select all its
neighbors as MPR - disabling the optimization sought by the MPR neighbors as MPR and disabling the optimization sought by the MPR
mechanism. mechanism.
.---. .---.
| B | | B |
'---' '---'
| |
| |
.---. .---. ..... .---. .---. .....
| A |----| X | . . . Y . | A |----| X | . . . Y .
'---' '---' ..... '---' '---' .....
spoofs B spoofs B
Figure 7 Figure 7
5.2. Routing Loops 5.2. Routing Loops
Inconsistent information bases, provided by NHDP to other protocols, Inconsistent information bases, provided by NHDP to other protocols,
can also cause routing loops. In Figure 8, the Compromised NHDP can also cause routing loops. In Figure 8, the compromised NHDP
router X spoofs the identity of NHDP router E. NHDP router D has data router X spoofs the identity of NHDP router E. NHDP router D has
traffic to send to NHDP router A. The topology recorded in the data traffic to send to NHDP router A. The topology recorded in the
information base of router D indicates that the shortest path to information base of router D indicates that the shortest path to
router A is {D->E->A}, because of the link {A-E} reported by X. router A is {D->E->A}, because of the link {A-E} reported by X.
Therefore, the data traffic will be routed to the NHDP router E. As Therefore, the data traffic will be routed to NHDP router E. As the
the link {A-E} does not exist in NHDP router E's information bases, link {A-E} does not exist in NHDP router E's information bases, it
it will identify the next hop for data traffic to NHDP router A as will identify the next hop for data traffic to NHDP router A as being
being NHDP router D. A loop between the NHDP routers D and E is thus NHDP router D. A loop between the NHDP routers D and E is thus
created. created.
.---. .---. .---. .---. .---. .---. .---. .---. .---. .---.
| A |----| B |----| C |----| D |----| E | | A |----| B |----| C |----| D |----| E |
'---' '---' '---' '---' '---' '---' '---' '---' '---' '---'
| |
| |
.---. .---.
| X | | X |
'---' '---'
spoofs E spoofs E
Figure 8 Figure 8
5.3. Invalid or Non-Existing Paths to Destinations 5.3. Invalid or Nonexistent Paths to Destinations
By reporting inconsistent topology information in NHDP, the invalid By reporting inconsistent topology information in NHDP, the invalid
links/routers can be propagated as link state information with TC links and routers can be propagated as link state information with
messages and results in route failure. As illustrated in Figure 8, traffic control messages and results in route failure. As
if NHDP router B tries to send data packets to NHDP router E, it will illustrated in Figure 8, if NHDP router B tries to send data packets
choose router A as its next hop, based on the information of non- to NHDP router E, it will choose router A as its next hop, based on
existing link {A-E} reported by the Compromised NHDP router X. the information about the nonexistent link {A-E} reported by the
compromised NHDP router X.
5.4. Data Sinkhole 5.4. Data Sinkhole
With the ability to spoof multiple identities of legitimate NHDP With the ability to spoof multiple identities of legitimate NHDP
routers (by eavesdropping, for example), the Compromised NHDP router routers (by eavesdropping, for example), the compromised NHDP router
can represent a "data sinkhole" for its 1-hop and 2-hop neighbors. can represent a "data sinkhole" for its 1-hop and 2-hop neighbors.
Data packets that come across its neighbors may be forwarded to the Data packets that come across its neighbors may be forwarded to the
Compromised NHDP router instead of to the real destination. The compromised NHDP router instead of to the real destination. The
packet can then be dropped, manipulated, duplicated, etc., by the packet can then be dropped, manipulated, duplicated, etc., by the
Compromised NHDP router. As shown in Figure 8, if the Compromised compromised NHDP router. As shown in Figure 8, if the compromised
NHDP router X spoofs the identity of NHDP router E, all the data NHDP router X spoofs the identity of NHDP router E, all the data
packets to E that cross NHDP routers A and B will be sent to NHDP packets to E that cross NHDP routers A and B will be sent to NHDP
router X, instead of to E. router X, instead of to E.
6. Future Work 6. Future Work
This document does not propose solutions to mitigate the security This document does not propose solutions to mitigate the security
threats described in Section 4. However, this section aims at threats described in Section 4. However, this section aims at
driving new work by suggesting which threats discussed in Section 4 driving new work by suggesting which threats discussed in Section 4
could be addressed in new protocol work, which in deployment, and could be addressed by deployments or applications.
which by applications:
o Section 4.1: Jamming - If a single router or a small area of the o Section 4.1: Jamming - If a single router or a small area of the
MANET is jammed, protocols could be specified that increase link MANET is jammed, protocols could be specified that increase link
metrics in NHDP for the jammed links. When a routing protocol, metrics in NHDP for the jammed links. When a routing protocol
such as OLSRv2, uses NHDP for neighborhood discovery, other paths such as OLSRv2 uses NHDP for neighborhood discovery, other paths
leading "around" the jammed area would be preferred, and therefore leading "around" the jammed area would be preferred, and therefore
mitigate the threat to some extent. would mitigate the threat to some extent.
o Section 4.2: DoS - DoS using a massive amount of HELLO messages o Section 4.2: DoS - A DoS attack using a massive amount of HELLO
can be mitigated by admitting only trusted routers to the network. messages can be mitigated by admitting only trusted routers to the
[I-D.ietf-manet-nhdp-olsrv2-sec] specifies a mechanism for adding network. [RFC7185] specifies a mechanism for adding Integrity
Integrity Check Values (ICVs) to HELLO messages and therefore Check Values (ICVs) to HELLO messages and therefore providing an
providing an admittance mechanism for NHDP Routers to a MANET. admittance mechanism for NHDP routers to a MANET. (Note that
(Note that adding ICVs adds itself a new DoS attack vector, as ICV adding ICVs creates a new DoS attack vector, as ICV verification
verification requires CPU and memory resources.) Using ICVs does requires CPU and memory resources.) However, using ICVs does not
however not address the problem of compromised routers. Detecting address the problem of compromised routers. Detecting compromised
compromised routers could be addressed in new work. routers could be addressed in new work. [RFC7185] mandates
[I-D.ietf-manet-nhdp-olsrv2-sec] mandates to implement a security implementation of a security mechanism that is based on shared
mechanism based on shared keys, which makes excluding single keys and makes excluding single compromised routers difficult;
compromised routers difficult; work could be done to facilitate work could be done to facilitate revocation mechanisms in certain
revocation mechanisms in certain MANET use cases where routers MANET use cases where routers have sufficient capabilities to
have sufficient capabilities to support asymmetric keys. support asymmetric keys.
o Section 4.3: Eavesdropping - [I-D.ietf-manet-nhdp-olsrv2-sec] adds o Section 4.3: Eavesdropping - [RFC7185] adds ICVs to HELLO messages
ICVs to HELLO messages, but does not encrypt them. Therefore, but does not encrypt them. Therefore, eavesdropping of control
eavesdropping of control traffic is not mitigated. Future work traffic is not mitigated. Future work could provide encryption of
could provide encryption of control traffic for sensitive MANET control traffic for sensitive MANET topologies. Note that, other
topologies. Note that, other than using a single shared secret than using a single shared secret key, providing encryption of
key, encryption to a potentially a priori unknown set of traffic among a set of neighbors (when that set is potentially
neighbors, especially without multiplying overheads, is non- undetermined) is nontrivial, especially without multiplying
trivial. By traffic analyzing, attackers could still deduce the overheads. With traffic analysis, attackers could still deduce
network information like HELLO message triggering, and HELLO the network information like HELLO message triggering and HELLO
message size, even HELLO messages are encrypted. message size, even though the HELLO messages are encrypted.
o Section 4.4.2: Link spoofing - [I-D.ietf-manet-nhdp-olsrv2-sec] o Section 4.4.2: Link spoofing - [RFC7185] provides certain
provides certain protection against link spoofing, but an NHDP protection against link spoofing, but an NHDP router has to
Router has to "trust" the originator of a HELLO that the "trust" the originator of a HELLO that the advertised links are
advertized links are correct. For example, if a router A reports correct. For example, if a router A reports a link to B, routers
a link to B, routers receiving HELLOs from A have to trust that B receiving HELLOs from A have to trust that B is actually a
is actually a (symmetric) neighbor of A. New protocol work could (symmetric) neighbor of A. New protocol work could address
address protection of links without overly increasing space and protection of links without overly increasing the space and time
time overheads. An immediate suggestion for deployments is to overheads. An immediate suggestion for deployments is to protect
protect routers against being compromised and distributing keys routers against being compromised and to distribute keys only to
only to trusted routers. trusted routers.
o Section 4.5: Replay Attacks - [I-D.ietf-manet-nhdp-olsrv2-sec] o Section 4.5: Replay Attacks - [RFC7185] uses ICVs and timestamps
provides certain protection against replay attacks, using ICVs and to provide some protection against replay attacks. It is still
timestamps. It is still feasible to replay control messages feasible to replay control messages within a limited time. A
within limited time. A suggestion for deployments is to provide suggestion for deployments is to provide time synchronization
time synchronization between routers. New work could provide time between routers. New work could provide time synchronization
synchronization mechanisms for certain MANET use cases, or specify mechanisms for certain MANET use cases or specify a mechanism
a mechanism using nonces instead of time stamps in HELLO messages. using nonces instead of timestamps in HELLO messages.
o Section 4.4.1: Identity spoofing, Section 4.6: Message timing o Section 4.4.1: Identity spoofing; Section 4.6: Message timing
attacks, Section 4.7: Indirect channel overloading, and attacks; Section 4.7: Indirect channel overloading; and
Section 4.8: Attack on link quality update - Section 4.8: Attack on link quality update - [RFC7185] provides
[I-D.ietf-manet-nhdp-olsrv2-sec] provides protection against these protection against these attacks, assuming the routers are not
attacks, assuming that routers are not compromised. compromised.
7. Security Considerations 7. Security Considerations
This document does not specify a protocol or a procedure. The This document does not specify a protocol or a procedure. The
document, however, reflects on security considerations for NHDP and document, however, reflects on security considerations for NHDP and
MANET routing protocols using NHDP for neighborhood discovery. MANET routing protocols using NHDP for neighborhood discovery.
8. IANA Considerations 8. Acknowledgments
This document contains no actions for IANA.
9. Acknowledgments
The authors would like to gratefully acknowledge the following people The authors would like to gratefully acknowledge the following people
for valuable comments and technical discussions: Teco Boot, Henning for valuable comments and technical discussions: Teco Boot, Henning
Rogge, Christopher Dearlove, John Dowdell, Joseph Macker, and the all Rogge, Christopher Dearlove, John Dowdell, Joseph Macker, and all the
the other participants of IETF MANET working group. other participants of the IETF MANET working group.
10. References 9. References
10.1. Normative References 9.1. Normative References
[RFC5444] Clausen, T., Dearlove, C., Dean, J., and C. Adjih, [RFC5444] Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
"Generalized Mobile Ad Hoc Network (MANET) Packet/Message "Generalized Mobile Ad Hoc Network (MANET) Packet/Message
Format", RFC 5444, February 2009. Format", RFC 5444, February 2009.
[RFC5497] Clausen, T. and C. Dearlove, "Representing Multi-Value [RFC5497] Clausen, T. and C. Dearlove, "Representing Multi-Value
Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497, Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497, March
March 2009. 2009.
[RFC6130] Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc [RFC6130] Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)", Network (MANET) Neighborhood Discovery Protocol (NHDP)",
RFC 6130, April 2011. RFC 6130, April 2011.
10.2. Informative References 9.2. Informative References
[ACCT2012] [ACCT2012] Jhaveri, R. and S. Patel, "DoS Attacks in Mobile Ad Hoc
Jhaveri, R. and S. Patel, "DoS Attacks in Mobile Ad Hoc Networks: A Survey", Second International Conference on
Networks: A Survey", Second International Conference Advanced Computing & Communication Technologies (ACCT),
on Advanced Computing & Communication Technologies (ACCT), January 2012.
Jan 2012.
[CPSCOM2011] [CPSCOM2011]
Yi, J., Clausen, T., and U. Herberg, "Vulnerability Yi, J., Clausen, T., and U. Herberg, "Vulnerability
Analysis of the Simple Multicast Forwarding (SMF) Protocol Analysis of the Simple Multicast Forwarding (SMF) Protocol
for Mobile Ad Hoc Networks", Proceedings of the IEEE for Mobile Ad Hoc Networks", Proceedings of the IEEE
International Conference on Cyber, Physical, and Social International Conference on Cyber, Physical, and Social
Computing (CPSCom), October 2011. Computing (CPSCom), October 2011.
[I-D.ietf-manet-nhdp-olsrv2-sec]
Herberg, U., Dearlove, C., and T. Clausen, "Integrity
Protection for Control Messages in NHDP and OLSRv2",
draft-ietf-manet-nhdp-olsrv2-sec-02 (work in progress),
April 2013.
[I-D.ietf-manet-olsrv2]
Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
"The Optimized Link State Routing Protocol version 2",
draft-ietf-manet-olsrv2-19 (work in progress), March 2013.
[I-D.nguyen-manet-management]
Nguyen, J., Cole, R., Herberg, U., Yi, J., and J. Dean,
"Network Management of Mobile Ad hoc Networks (MANET):
Architecture, Use Cases, and Applicability",
draft-nguyen-manet-management-00 (work in progress),
February 2013.
[IJNSIA2010] [IJNSIA2010]
Herberg, U. and T. Clausen, "Security Issues in the Herberg, U. and T. Clausen, "Security Issues in the
Optimized Link State Routing Protocol version 2", Optimized Link State Routing Protocol version 2",
International Journal of Network Security & Its International Journal of Network Security & Its
Applications, April 2010. Applications, April 2010.
[MANET-MGMT]
Nguyen, J., Cole, R., Herberg, U., Yi, J., and J. Dean,
"Network Management of Mobile Ad hoc Networks (MANET):
Architecture, Use Cases, and Applicability", Work in
Progress, February 2013.
[MGMT-SNAP]
Clausen, T. and U. Herberg, "Snapshot of OLSRv2-Routed
MANET Management", Work in Progress, February 2014.
[MOBICOM99] [MOBICOM99]
Ni, S., Tseng, Y., Chen, Y., and J. Sheu, "The Broadcast Ni, S., Tseng, Y., Chen, Y., and J. Sheu, "The Broadcast
Storm Problem in a Mobile Ad Hoc Network", Proceedings of Storm Problem in a Mobile Ad Hoc Network", Proceedings of
the 5th annual ACM/IEEE international conference on Mobile the 5th annual ACM/IEEE international conference on Mobile
computing and networking, 1999. computing and networking, 1999.
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to [RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
Routing Protocols", RFC 4593, October 2006. Routing Protocols", RFC 4593, October 2006.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2", [RFC4949] Shirey, R., "Internet Security Glossary, Version 2", RFC
RFC 4949, August 2007. 4949, August 2007.
[RFC6621] Macker, J., "Simplified Multicast Forwarding", RFC 6621, [RFC6621] Macker, J., "Simplified Multicast Forwarding", RFC 6621,
May 2012. May 2012.
[RFC6779] Herberg, U., Cole, R., and I. Chakeres, "Definition of [RFC6779] Herberg, U., Cole, R., and I. Chakeres, "Definition of
Managed Objects for the Neighborhood Discovery Protocol", Managed Objects for the Neighborhood Discovery Protocol",
RFC 6779, October 2012. RFC 6779, October 2012.
[RFC7181] Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
"The Optimized Link State Routing Protocol Version 2", RFC
7181, April 2014.
[RFC7185] Herberg, U., Dearlove, C., and T. Clausen, "Integrity
Protection for the Neighborhood Discovery Protocol (NHDP)
and Optimized Link State Routing Protocol Version 2
(OLSRv2)", RFC 7185, April 2014.
Authors' Addresses Authors' Addresses
Jiazi Yi Jiazi Yi
LIX, Ecole Polytechnique LIX, Ecole Polytechnique
91128 Palaiseau Cedex, 91128 Palaiseau Cedex
France France
Phone: +33 1 77 57 80 85 Phone: +33 1 77 57 80 85
Email: jiazi@jiaziyi.com EMail: jiazi@jiaziyi.com
URI: http://www.jiaziyi.com/ URI: http://www.jiaziyi.com/
Ulrich Herberg Ulrich Herberg
Fujitsu Laboratories of America Fujitsu Laboratories of America
1240 E Arques Ave 1240 E Arques Ave
Sunnyvale, CA 94085 Sunnyvale, CA 94085
USA USA
Email: ulrich@herberg.name EMail: ulrich@herberg.name
URI: http://www.herberg.name/ URI: http://www.herberg.name/
Thomas Heide Clausen Thomas Heide Clausen
LIX, Ecole Polytechnique LIX, Ecole Polytechnique
91128 Palaiseau Cedex, 91128 Palaiseau Cedex
France France
Phone: +33 6 6058 9349 Phone: +33 6 6058 9349
Email: T.Clausen@computer.org EMail: T.Clausen@computer.org
URI: http://www.thomasclausen.org/ URI: http://www.thomasclausen.org/
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