Internet DRAFT - draft-sdt-detnet-security
draft-sdt-detnet-security
Internet Engineering Task Force T. Mizrahi
Internet-Draft MARVELL
Intended status: Informational E. Grossman, Ed.
Expires: January 3, 2018 DOLBY
A. Hacker
MISTIQ
S. Das
Applied Communication Sciences
J. Dowdell
Airbus Defence and Space
H. Austad
Cisco Systems
K. Stanton
INTEL
N. Finn
HUAWEI
July 2, 2017
Deterministic Networking (DetNet) Security Considerations
draft-sdt-detnet-security-01
Abstract
A deterministic network is one that can carry data flows for real-
time applications with extremely low data loss rates and bounded
latency. Deterministic networks have been successfully deployed in
real-time operational technology (OT) applications for some years
(for example [ARINC664P7]). However, such networks are typically
isolated from external access, and thus the security threat from
external attackers is low. IETF Deterministic Networking (DetNet)
specifies a set of technologies that enable creation of deterministic
networks on IP-based networks of potentially wide area (on the scale
of a corporate network) potentially bringing the OT network into
contact with Information Technology (IT) traffic and security threats
that lie outside of a tightly controlled and bounded area (such as
the internals of an aircraft). These DetNet technologies have not
previously been deployed together on a wide area IP-based network,
and thus can present security considerations that may be new to IP-
based wide area network designers. This draft, intended for use by
DetNet network designers, provides insight into these security
considerations. In addition, this draft collects all security-
related statements from the various DetNet drafts (Architecture, Use
Cases, etc) into a single location Section 7.
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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
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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 January 3, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Security Threats . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Threat Model . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Threat Analysis . . . . . . . . . . . . . . . . . . . . . 7
3.2.1. Delay . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1.1. Delay Attack . . . . . . . . . . . . . . . . . . 7
3.2.2. DetNet Flow Identification . . . . . . . . . . . . . 7
3.2.2.1. DetNet Flow Modification or Spoofing . . . . . . 7
3.2.3. Resource Segmentation or Slicing . . . . . . . . . . 7
3.2.3.1. Inter-segment Attack . . . . . . . . . . . . . . 7
3.2.4. Packet Replication and Elimination . . . . . . . . . 7
3.2.4.1. Replication: Increased Attack Surface . . . . . . 8
3.2.4.2. Replication-related Header Manipulation . . . . . 8
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3.2.5. Path Choice . . . . . . . . . . . . . . . . . . . . . 8
3.2.5.1. Path Manipulation . . . . . . . . . . . . . . . . 8
3.2.5.2. Path Choice: Increased Attack Surface . . . . . . 8
3.2.6. Control Plane . . . . . . . . . . . . . . . . . . . . 9
3.2.6.1. Control or Signaling Packet Modification . . . . 9
3.2.6.2. Control or Signaling Packet Injection . . . . . . 9
3.2.7. Scheduling or Shaping . . . . . . . . . . . . . . . . 9
3.2.7.1. Reconnaissance . . . . . . . . . . . . . . . . . 9
3.2.8. Time Synchronization Mechanisms . . . . . . . . . . . 9
3.3. Threat Summary . . . . . . . . . . . . . . . . . . . . . 9
4. Security Threat Impacts . . . . . . . . . . . . . . . . . . . 10
4.1. Delay-Attacks . . . . . . . . . . . . . . . . . . . . . . 10
4.1.1. Data Plane Delay Attacks . . . . . . . . . . . . . . 11
4.1.2. Control Plane Delay Attacks . . . . . . . . . . . . . 11
4.2. Flow Identification and Spoofing . . . . . . . . . . . . 11
4.2.1. Flow identification . . . . . . . . . . . . . . . . . 11
4.2.2. Spoofing . . . . . . . . . . . . . . . . . . . . . . 12
4.2.2.1. Dataplane Spoofing . . . . . . . . . . . . . . . 12
4.2.2.2. Control Plane Spoofing . . . . . . . . . . . . . 12
4.3. Segmentation attacks (injection) . . . . . . . . . . . . 12
4.3.1. Data Plane Segmentation . . . . . . . . . . . . . . . 12
4.3.2. Control Plane segmentation . . . . . . . . . . . . . 13
4.4. Replication and Elimination . . . . . . . . . . . . . . . 13
4.4.1. Increased Attack Surface . . . . . . . . . . . . . . 13
4.4.2. Header Manipulation at Elimination Bridges . . . . . 13
4.5. Impact of Attacks to Path Choice . . . . . . . . . . . . 13
4.6. Impact of Attacks by Use Case Industry . . . . . . . . . 13
5. Security Threat Mitigation . . . . . . . . . . . . . . . . . 15
5.1. Path Redundancy . . . . . . . . . . . . . . . . . . . . . 16
5.2. Integrity Protection . . . . . . . . . . . . . . . . . . 16
5.3. DetNet Node Authentication . . . . . . . . . . . . . . . 16
5.4. Encryption . . . . . . . . . . . . . . . . . . . . . . . 17
5.5. Control and Signaling Message Protection . . . . . . . . 17
5.6. Dynamic Performance Analytics . . . . . . . . . . . . . . 17
5.7. Mitigation Summary . . . . . . . . . . . . . . . . . . . 18
6. Association of Attacks to Use Cases . . . . . . . . . . . . . 19
6.1. Use Cases by Common Themes . . . . . . . . . . . . . . . 19
6.1.1. Network Layer - AVB/TSN Ethernet . . . . . . . . . . 19
6.1.2. Central Administration . . . . . . . . . . . . . . . 19
6.1.3. Hot Swap . . . . . . . . . . . . . . . . . . . . . . 20
6.1.4. Data Flow Information Models . . . . . . . . . . . . 20
6.1.5. L2 and L3 Integration . . . . . . . . . . . . . . . . 20
6.1.6. End-to-End Delivery . . . . . . . . . . . . . . . . . 20
6.1.7. Proprietary Deterministic Ethernet Networks . . . . . 20
6.1.8. Replacement for Proprietary Fieldbuses . . . . . . . 20
6.1.9. Deterministic vs Best-Effort Traffic . . . . . . . . 21
6.1.10. Deterministic Flows . . . . . . . . . . . . . . . . . 21
6.1.11. Unused Reserved Bandwidth . . . . . . . . . . . . . . 21
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6.1.12. Interoperability . . . . . . . . . . . . . . . . . . 21
6.1.13. Cost Reductions . . . . . . . . . . . . . . . . . . . 21
6.1.14. Insufficiently Secure Devices . . . . . . . . . . . . 22
6.1.15. DetNet Network Size . . . . . . . . . . . . . . . . . 22
6.1.16. Multiple Hops . . . . . . . . . . . . . . . . . . . . 22
6.1.17. Level of Service . . . . . . . . . . . . . . . . . . 22
6.1.18. Bounded Latency . . . . . . . . . . . . . . . . . . . 23
6.1.19. Low Latency . . . . . . . . . . . . . . . . . . . . . 23
6.1.20. Symmetrical Path Delays . . . . . . . . . . . . . . . 23
6.1.21. Reliability and Availability . . . . . . . . . . . . 23
6.1.22. Redundant Paths . . . . . . . . . . . . . . . . . . . 24
6.1.23. Security Measures . . . . . . . . . . . . . . . . . . 24
6.2. Attack Types by Use Case Common Theme . . . . . . . . . . 24
7. Appendix A: DetNet Draft Security-Related Statements . . . . 26
7.1. Architecture (draft 8) . . . . . . . . . . . . . . . . . 27
7.1.1. Fault Mitigation (sec 4.5) . . . . . . . . . . . . . 27
7.1.2. Security Considerations (sec 7) . . . . . . . . . . . 27
7.2. Data Plane Alternatives (draft 4) . . . . . . . . . . . . 28
7.2.1. Security Considerations (sec 7) . . . . . . . . . . . 28
7.3. Problem Statement (draft 5) . . . . . . . . . . . . . . . 28
7.3.1. Security Considerations (sec 5) . . . . . . . . . . . 28
7.4. Use Cases (draft 11) . . . . . . . . . . . . . . . . . . 29
7.4.1. (Utility Networks) Security Current Practices and
Limitations (sec 3.2.1) . . . . . . . . . . . . . . . 29
7.4.2. (Utility Networks) Security Trends in Utility
Networks (sec 3.3.3) . . . . . . . . . . . . . . . . 30
7.4.3. (BAS) Security Considerations (sec 4.2.4) . . . . . . 32
7.4.4. (6TiSCH) Security Considerations (sec 5.3.3) . . . . 32
7.4.5. (Cellular radio) Security Considerations (sec 6.1.5) 32
7.4.6. (Industrial M2M) Communication Today (sec 7.2) . . . 33
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
9. Security Considerations . . . . . . . . . . . . . . . . . . . 33
10. Informative References . . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction
Security is of particularly high importance in DetNet networks
because many of the use cases which are enabled by DetNet
[I-D.ietf-detnet-use-cases] include control of physical devices
(power grid components, industrial controls, building controls) which
can have high operational costs for failure, and present potentially
attractive targets for cyber-attackers.
This situation is even more acute given that one of the goals of
DetNet is to provide a "converged network", i.e. one that includes
both IT traffic and OT traffic, thus exposing potentially sensitive
OT devices to attack in ways that were not previously common (usually
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because they were under a separate control system or otherwise
isolated from the IT network). Security considerations for OT
networks is not a new area, and there are many OT networks today that
are connected to wide area networks or the Internet; this draft
focuses on the issues that are specific to the DetNet technologies
and use cases.
The DetNet technologies include ways to:
o Reserve data plane resources for DetNet flows in some or all of
the intermediate nodes (e.g. bridges or routers) along the path of
the flow
o Provide explicit routes for DetNet flows that do not rapidly
change with the network topology
o Distribute data from DetNet flow packets over time and/or space to
ensure delivery of each packet's data' in spite of the loss of a
path
This draft includes sections on threat modeling and analysis, threat
impact and mitigation, and the association of various attacks with
various use cases both by industry and based on the Use Case Common
Themes section of the DetNet Use Cases draft
[I-D.ietf-detnet-use-cases].
This draft also provides context for the DetNet security
considerations by collecting into one place Section 7 the various
remarks about security from the various DetNet drafts (Use Cases,
Architecture, etc). This text is duplicated here primarily because
the DetNet working group has elected not to produce a Requirements
draft and thus collectively these statements are as close as we have
to "DetNet Security Requirements".
2. Abbreviations
IT Information technology (the application of computers to
store, study, retrieve, transmit, and manipulate data or information,
often in the context of a business or other enterprise - Wikipedia).
OT Operational Technology (the hardware and software
dedicated to detecting or causing changes in physical processes
through direct monitoring and/or control of physical devices such as
valves, pumps, etc. - Wikipedia)
MITM Man in the Middle
SN Sequence Number
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STRIDE Addresses risk and severity associated with threat
categories: Spoofing identity, Tampering with data, Repudiation,
Information disclosure, Denial of service, Elevation of privilege.
DREAD Compares and prioritizes risk represented by these threat
categories: Damage potential, Reproducibility, Exploitability, how
many Affected users, Discoverability.
PTP Precision Time Protocol [IEEE1588]
3. Security Threats
This section presents a threat model, and analyzes the possible
threats in a DetNet-enabled network.
We distinguish control plane threats from data plane threats. The
attack surface may be the same, but the types of attacks are
different. For example, a delay attack is more relevant to data
plane than to control plane. There is also a difference in terms of
security solutions: the way you secure the data plane is often
different than the way you secure the control plane.
3.1. Threat Model
The threat model used in this memo is based on the threat model of
Section 3.1 of [RFC7384]. This model classifies attackers based on
two criteria:
o Internal vs. external: internal attackers either have access to a
trusted segment of the network or possess the encryption or
authentication keys. External attackers, on the other hand, do
not have the keys and have access only to the encrypted or
authenticated traffic.
o Man in the Middle (MITM) vs. packet injector: MITM attackers are
located in a position that allows interception and modification of
in-flight protocol packets, whereas a traffic injector can only
attack by generating protocol packets.
DetNet-Service, one of the service scenarios described in
[I-D.varga-detnet-service-model], is the case where a service
connects DetNet networking islands, i.e. two or more otherwise
independent DetNet network domains are connected via a link that is
not intrinsically part of either network. This implies that there
could be DetNet traffic flowing over a non-DetNet link, which may
provide an attacker with an advantageous opportunity to tamper with
DetNet traffic. The security properties of non-DetNet links are
outside of the scope of DetNet Security, but it should be noted that
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use of non-DetNet services to interconnect DetNet networks merits
security analysis to ensure the integrity of the DetNet networks
involved.
3.2. Threat Analysis
3.2.1. Delay
3.2.1.1. Delay Attack
An attacker can maliciously delay DetNet data flow traffic. By
delaying the traffic, the attacker can compromise the service of
applications that are sensitive to high delays or to high delay
variation.
3.2.2. DetNet Flow Identification
3.2.2.1. DetNet Flow Modification or Spoofing
An attacker can modify some header fields of en route packets in a
way that causes the DetNet flow identification mechanisms to
misclassify the flow. Alternatively, the attacker can inject traffic
that is tailored to appear as if it belongs to a legitimate DetNet
flow. The potential consequence is that the DetNet flow resource
allocation cannot guarantee the performance that is expected when the
flow identification works correctly.
Note that in some cases there may be an explicit DetNet header, but
in some cases the flow identification may be based on fields from the
L3/L4 headers. If L3/L4 headers are involved, for purposes of this
draft we assume they are encrypted and/or integrity-protected from
external attackers.
3.2.3. Resource Segmentation or Slicing
3.2.3.1. Inter-segment Attack
An attacker can inject traffic, consuming network device resources,
thereby affecting DetNet flows. This can be performed using non-
DetNet traffic that affects DetNet traffic, or by using DetNet
traffic from one DetNet flow that affects traffic from different
DetNet flows.
3.2.4. Packet Replication and Elimination
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3.2.4.1. Replication: Increased Attack Surface
Redundancy is intended to increase the robustness and survivability
of DetNet flows, and replication over multiple paths can potentially
mitigate an attack that is limited to a single path. However, the
fact that packets are replicated over multiple paths increases the
attack surface of the network, i.e., there are more points in the
network that may be subject to attacks.
3.2.4.2. Replication-related Header Manipulation
An attacker can manipulate the replication-related header fields
(R-TAG). This capability opens the door for various types of
attacks. For example:
o Forward both replicas - malicious change of a packet SN (Sequence
Number) can cause both replicas of the packet to be forwarded.
Note that this attack has a similar outcome to a replay attack.
o Eliminate both replicas - SN manipulation can be used to cause
both replicas to be eliminated. In this case an attacker that has
access to a single path can cause packets from other paths to be
dropped, thus compromising some of the advantage of path
redundancy.
o Flow hijacking - an attacker can hijack a DetNet flow with access
to a single path by systematically replacing the SNs on the given
path with higher SN values. For example, an attacker can replace
every SN value S with a higher value S+C, where C is a constant
integer. Thus, the attacker creates a false illusion that the
attacked path has the lowest delay, causing all packets from other
paths to be eliminated. Once the flow is hijacked the attacker
can either replace en route packets with malicious packets, or
simply injecting errors, causing the packets to be dropped at
their destination.
3.2.5. Path Choice
3.2.5.1. Path Manipulation
An attacker can maliciously change, add, or remove a path, thereby
affecting the corresponding DetNet flows that use the path.
3.2.5.2. Path Choice: Increased Attack Surface
One of the possible consequences of a path manipulation attack is an
increased attack surface. Thus, when the attack described in the
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previous subsection is implemented, it may increase the potential of
other attacks to be performed.
3.2.6. Control Plane
3.2.6.1. Control or Signaling Packet Modification
An attacker can maliciously modify en route control packets in order
to disrupt or manipulate the DetNet path/resource allocation.
3.2.6.2. Control or Signaling Packet Injection
An attacker can maliciously inject control packets in order to
disrupt or manipulate the DetNet path/resource allocation.
3.2.7. Scheduling or Shaping
3.2.7.1. Reconnaissance
A passive eavesdropper can gather information about en route DetNet
flows, e.g., the number of DetNet flows, their bandwidths, and their
schedules. The gathered information can later be used to invoke
other attacks on some or all of the flows.
3.2.8. Time Synchronization Mechanisms
An attacker can use any of the attacks described in [RFC7384] to
attack the synchronization protocol, thus affecting the DetNet
service.
3.3. Threat Summary
A summary of the attacks that were discussed in this section is
presented in Figure 1. For each attack, the table specifies the type
of attackers that may invoke the attack. In the context of this
summary, the distinction between internal and external attacks is
under the assumption that a corresponding security mechanism is being
used, and that the corresponding network equipment takes part in this
mechanism.
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+-----------------------------------------+----+----+----+----+
| Attack | Attacker Type |
| +---------+---------+
| |Internal |External |
| |MITM|Inj.|MITM|Inj.|
+-----------------------------------------+----+----+----+----+
|Delay attack | + | | + | |
+-----------------------------------------+----+----+----+----+
|DetNet Flow Modification or Spoofing | + | + | | |
+-----------------------------------------+----+----+----+----+
|Inter-segment Attack | + | + | | |
+-----------------------------------------+----+----+----+----+
|Replication: Increased Attack Surface | + | + | + | + |
+-----------------------------------------+----+----+----+----+
|Replication-related Header Manipulation | + | | | |
+-----------------------------------------+----+----+----+----+
|Path Manipulation | + | + | | |
+-----------------------------------------+----+----+----+----+
|Path Choice: Increased Attack Surface | + | + | + | + |
+-----------------------------------------+----+----+----+----+
|Control or Signaling Packet Modification | + | | | |
+-----------------------------------------+----+----+----+----+
|Control or Signaling Packet Injection | | + | | |
+-----------------------------------------+----+----+----+----+
|Reconnaissance | + | | + | |
+-----------------------------------------+----+----+----+----+
|Attacks on Time Sync Mechanisms | + | + | + | + |
+-----------------------------------------+----+----+----+----+
Figure 1: Threat Analysis Summary
4. Security Threat Impacts
This section describes the impact of the attacks described in
Section 3. Mitigations are discussed further in Section 5.
In computer security, the impact (or consequence) of an incident can
be measured in loss of confidentiality, integrity or availability of
information. In other words, this section describes the effect of a
successful attack. The scope is limited to the effect of a
successful attack on DetNet itself, not the applications that _use_
Detnet as this is highly application specific.
4.1. Delay-Attacks
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4.1.1. Data Plane Delay Attacks
Dropped messages can result in stream instability. If only a single
path is used, the entire stream can be disrupted. In a multipath
scenario, large delays on one stream can lead to increased buffer and
CPU resources on the elimination bridge.
If the attack is carried out on a sole link (i.e. no multipath), the
DetNet stream can be interrupted and result in outages.
4.1.2. Control Plane Delay Attacks
In and of itself, this is not directly a threat, the effects of
delaying control messages can have quite adverse effects later.
Delayed messages for tear-down can lead to resource leakage if a
stream is not torn down at the correct time. This can in turn result
in failure to allocate new streams giving rise to a denial of service
attack.
In the case where an End-point should be added to a multicast,
failure to deliver said signalling message will prevent the new EP
from receiving expected frames.
Likewise, when an EP should be removed from a multicast group,
delaying such messages can lead to loss of privacy as the EP will
continue to receive messages even after it is removed.
4.2. Flow Identification and Spoofing
4.2.1. Flow identification
Of all the attacks, this is one of the most difficult to detect and
counter. Often, an attacker will start out by observing the traffic
going through the network and use the knowledge gathered in this
phase to mount future attacks.
The attacker can, at their leisure, observe over time all aspects of
the messaging and signalling, learning the intent and purpose of all
traffic flows. At some later date, possibly at an important time in
an operational context, the attacker can launch a multi-faceted
attack, possibly in conjunction with some demand for ransom.
The flow-id in the header of the data plane-messages gives an
attacker a very reliable identifier for DetNet traffic, and this
traffic has a high probability of going to lucrative targets.
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4.2.2. Spoofing
4.2.2.1. Dataplane Spoofing
Spoofing dataplane messages can result in increased resource
consumptions on the bridges throughout the network as it will
increase buffer usage and CPU utilization. This can lead to resource
exhaustion and/or increased delay.
If the attacker manages to create valid headers, the false messages
can be forwarded through the network, using part of the allocated
bandwidth. This in turn can cause legitimate messages to be dropped
when the budget has been exhausted.
Finally, the endpoint will have to deal with invalid messages being
delivered to the endpoint instead of (or in addition to) a valid
message.
4.2.2.2. Control Plane Spoofing
A successful control plane spoofing-attack has a very large
potential. It can do anything from modifying existing streams by
changing the available bandwidth, add or remove endpoints or drop the
stream altogether. It would also be possible to falsely create new
streams, which could give an attacker the ability to exhaust the
systems resources, or just enable a high quality DetNet stream
outside the Network engineer's control.
4.3. Segmentation attacks (injection)
4.3.1. Data Plane Segmentation
Injection of false messages in a DetNet stream could lead to
exhaustion of the available bandwidth for a stream if the bridges
accounts false messages to the stream's budget.
In a multipath scenario, injected messages will cause an increased
CPU utilization on elimination bridges and if enough paths are
subject to malicious injection, the legitimate messages could be
dropped. Likewise it can cause an increase in buffer usage. In
total, this will consume more resources on the bridges than normal,
giving rise to a potential resource exhaustion attack on the bridges.
If a stream is interrupted, the end application will be affected by
what is now a non-deterministic stream.
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4.3.2. Control Plane segmentation
A successful Control Plane segmentation attack will cause control
messages to be interpreted by nodes in the network. This has the
potential to create new streams (exhausting resources), drop existing
(denial of service), add/remove end-stations to a multicast group
(loss of privacy) or modify the stream attributes (reducing available
bandwidth, or increasing it so that new streams cannot reserve a
path).
In short, this means that you cannot trust the stream reservation
properties or the network itself.
As with spoofing, if an attacker is able to inject control-plane
messages and the receiving end does not detect it, the receiving
station must be able to.
4.4. Replication and Elimination
The Replication and Elimination is relevant only to Data Plane
messages as Signalling is not subject to multipath routing.
4.4.1. Increased Attack Surface
Covered briefly in Section 4.3
4.4.2. Header Manipulation at Elimination Bridges
Covered briefly in Section 4.3
4.5. Impact of Attacks to Path Choice
This is covered in part in Section 4.3, and as with Replication and
Elimination (Section 4.4, this is relevant for DataPlane messages.
4.6. Impact of Attacks by Use Case Industry
This section rates the severity of various components of the impact
of a successful vulnerability exploit to use cases by industry as
described in [I-D.ietf-detnet-use-cases], including Pro Audio,
Electrical Utilities, Building Automation, Wireless for Industrial,
Cellular Radio, and Industrial M2M (split into two areas, M2M Data
Gathering and M2M Control Loop).
Components of Impact (left column) include Criticality of Failure,
Effects of Failure, Recovery, and DetNet Functional Dependence.
Criticality of failure summarizes the seriousness of the impact. The
impact of a resulting failure can affect many different metrics that
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vary greatly in scope and severity. In order to reduce the number of
variables, the following were included: Financial, Health and Safety,
People well being, Affect on a single organization, and affect on
multiple organizations. Recovery outlines how long it would take for
an affected use case to get back to its pre-failure state (Recovery
time objective, RTO), and how much of the original service would be
lost in between the time of service failure and recovery to original
state (Recovery Point Objective, RPO). DetNET dependence maps how
much the following DetNet service objectives contribute to impact of
failure: Time dependency, data integrity, source node integrity,
availability, latency/jitter.
The scale of the Impact mappings is low, medium, and high. In some
use cases there may be a multitude of specific applications in which
DetNET is used. For simplicity this section attempts to average the
varied impacts of different applications. This section does not
address the overall risk of a certain impact which would require the
likelihood of a failure happening.
In practice any such ratings will vary from case to case; the ratings
shown here are given as examples.
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+------------------+-----------------------------------------+-----+
| | Pro A | Util | Bldg |Wire- | Cell |M2M |M2M |
| | | | | less | |Data |Ctrl |
+------------------+-----------------------------------------+-----+
| Criticality | Med | Hi | Low | Med | Med | Med | Med |
+------------------+-----------------------------------------+-----+
| Effects
+------------------+-----------------------------------------+-----+
| Financial | Med | Hi | Med | Med | Low | Med | Med |
+------------------+-----------------------------------------+-----+
| Health/Safety | Med | Hi | Hi | Med | Med | Med | Med |
+------------------+-----------------------------------------+-----+
| People WB | Med | Hi | Hi | Low | Hi | Low | Low |
+------------------+-----------------------------------------+-----+
| Effect 1 org | Hi | Hi | Med | Hi | Med | Med | Med |
+------------------+-----------------------------------------+-----+
| Effect >1 org | Med | Hi | Low | Med | Med | Med | Med |
+------------------+-----------------------------------------+-----+
|Recovery
+------------------+-----------------------------------------+-----+
| Recov Time Obj | Med | Hi | Med | Hi | Hi | Hi | Hi |
+------------------+-----------------------------------------+-----+
| Recov Point Obj | Med | Hi | Low | Med | Low | Hi | Hi |
+------------------+-----------------------------------------+-----+
|DetNet Dependence
+------------------+-----------------------------------------+-----+
| Time Dependency | Hi | Hi | Low | Hi | Med | Low | Hi |
+------------------+-----------------------------------------+-----+
| Latency/Jitter | Hi | Hi | Med | Med | Low | Low | Hi |
+------------------+-----------------------------------------+-----+
| Data Integrity | Hi | Hi | Med | Hi | Low | Hi | Low |
+------------------+-----------------------------------------+-----+
| Src Node Integ | Hi | Hi | Med | Hi | Med | Hi | Hi |
+------------------+-----------------------------------------+-----+
| Availability | Hi | Hi | Med | Hi | Low | Hi | Hi |
+------------------+-----------------------------------------+-----+
Figure 2: Impact of Attacks by Use Case Industry
5. Security Threat Mitigation
This section describes a set of measures that can be taken to
mitigate the attacks described in Section 3. These mitigations
should be viewed as a toolset that includes several different and
diverse tools. Each application or system will typically use a
subset of these tools, based on a system-specific threat analysis.
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5.1. Path Redundancy
Description
A DetNet flow that can be forwarded simultaneously over multiple
paths. Path replication and elimination
[I-D.ietf-detnet-architecture] provides resiliency to dropped or
delayed packets. This redundancy improves the robustness to
failures and to man-in-the-middle attacks.
Related attacks
Path redundancy can be used to mitigate various man-in-the-middle
attacks, including attacks described in Section 3.2.1,
Section 3.2.2, Section 3.2.3, and Section 3.2.8.
5.2. Integrity Protection
Description
An integrity protection mechanism, such as a Hash-based Message
Authentication Code (HMAC) can be used to mitigate modification
attacks. Integrity protection can be used on the data plane
header, to prevent its modification and tampering. Integrity
protection in the control plane is discussed in Section 5.5.
Related attacks
Integrity protection mitigates attacks related to modification and
tampering, including the attacks described in Section 3.2.2 and
Section 3.2.4.
5.3. DetNet Node Authentication
Description
Source authentication verifies the authenticity of DetNet sources,
allowing to mitigate spoofing attacks. Note that while integrity
protection (Section 5.2) prevents intermediate nodes from
modifying information, authentication verfies the source of the
information.
Related attacks
DetNet node authentication is used to mitigate attacks related to
spoofing, including the attacks of Section 3.2.2, and
Section 3.2.4.
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5.4. Encryption
Description
DetNet flows can be forwarded in encrypted form.
Related attacks
While confidentiality is not considered an important goal with
respect to DetNet, encryption can be used to mitigate recon
attacks (Section 3.2.7).
5.5. Control and Signaling Message Protection
Description
Control and sigaling messages can be protected using
authentication and integrity protection mechanisms.
Related attacks
These mechanisms can be used to mitigate various attacks on the
control plane, as described in Section 3.2.6, Section 3.2.8 and
Section 3.2.5.
5.6. Dynamic Performance Analytics
Description
Information about the network performance can be gathered in real-
time in order to detect anomalies and unusual behavior that may be
the symptom of a security attack. The gathered information can be
based, for example, on per-flow counters, bandwidth measurement,
and monitoring of packet arrival times. Unusual behavior or
potentially malicious nodes can be reported to a management
system, or can be used as a trigger for taking corrective actions.
The information can be tracked by DetNet end systems and transit
nodes, and exported to a management system, for example using
NETCONF.
Related attacks
Performance analytics can be used to mitigate various attacks,
including the ones described in Section 3.2.1, Section 3.2.3, and
Section 3.2.8.
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5.7. Mitigation Summary
The following table maps the attacks of Section 3 to the impacts of
Section 4, and to the mitigations of the current section. Each row
specifies an attack, the impact of this attack if it is successfully
implemented, and possible mitigation methods.
+----------------------+---------------------+---------------------+
| Attack | Impact | Mitigations |
+----------------------+---------------------+---------------------+
|Delay Attack |-Non-deterministic |-Path redundancy |
| | delay |-Performance |
| |-Data disruption | analytics |
| |-Increased resource | |
| | consumption | |
+----------------------+---------------------+---------------------+
|DetNet Flow Modificat-|-Increased resource |-Path redundancy |
|ion or Spoofing | consumption |-Integrity protection|
| |-Data disruption |-DetNet Node |
| | | authentication |
+----------------------+---------------------+---------------------+
|Inter-Segment Attack |-Increased resource |-Path redundancy |
| | consumption |-Performance |
| |-Data disruption | analytics |
+----------------------+---------------------+---------------------+
|Replication: Increased|-All impacts of other|-Integrity protection|
|attack surface | attacks |-DetNet Node |
| | | authentication |
+----------------------+---------------------+---------------------+
|Replication-related |-Non-deterministic |-Integrity protection|
|Header Manipulation | delay |-DetNet Node |
| |-Data disruption | authentication |
+----------------------+---------------------+---------------------+
|Path Manipulation |-Enabler for other |-Control message |
| | attacks | protection |
+----------------------+---------------------+---------------------+
|Path Choice: Increased|-All impacts of other|-Control message |
|Attack Surface | attacks | protection |
+----------------------+---------------------+---------------------+
|Control or Signaling |-Increased resource |-Control message |
|Packet Modification | consumption | protection |
| |-Non-deterministic | |
| | delay | |
| |-Data disruption | |
+----------------------+---------------------+---------------------+
|Control or Signaling |-Increased resource |-Control message |
|Packet Injection | consumption | protection |
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| |-Non-deterministic | |
| | delay | |
| |-Data disruption | |
+----------------------+---------------------+---------------------+
|Reconnaissance |-Enabler for other |-Encryption |
| | attacks | |
+----------------------+---------------------+---------------------+
|Attacks on Time Sync |-Non-deterministic |-Path redundancy |
|Mechanisms | delay |-Control message |
| |-Increased resource | protection |
| | consumption |-Performance |
| |-Data disruption | analytics |
+----------------------+---------------------+---------------------+
Figure 3: Mapping Attacks to Impact and Mitigations
6. Association of Attacks to Use Cases
6.1. Use Cases by Common Themes
Different attacks can have different impact and/or mitigation
depending on the use case, so we would like to make this association
in our analysis. However since there is a potentially unbounded list
of use cases, we categorize the attacks with respect to the common
themes of the use cases as identified in the Use Case Common Themes
section of the DetNet Use Cases draft [I-D.ietf-detnet-use-cases].
We describe each theme and its associated attacks, impacts and
mitigations.
6.1.1. Network Layer - AVB/TSN Ethernet
Presumably it will be possible to run DetNet over other underlying
network layers besides Ethernet, but Ethernet is explicitly
supported. Is the attack specific to the Ethernet AVB/TSN protocols?
Does the threat affect only Ethernet, or any underlying network
layer?
6.1.2. Central Administration
A DetNet network is expected to be controlled by a centralized
network configuration and control system. Such a system may be in a
single central location, or it may be distributed across multiple
control entities that function together as a unified control system
for the network. Is the attack directed at threat the central
control system of the network? Does it interfere with OAM?
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6.1.3. Hot Swap
A DetNet network is not expected to be "plug and play" - it is
expected that there is some centralized network configuration and
control system. However, the ability to "hot swap" components (e.g.
due to malfunction) is similar enough to "plug and play" that this
kind of behavior may be expected in DetNet networks, depending on the
implementation. Does the attack target "hot swap" ("plug and play")
operation in the network?
6.1.4. Data Flow Information Models
Data Flow Information Models specific to DetNet networks are to be
specified by DetNet. Thus they are "new" and thus potentially
present a new attack surface. Does the threat take advantage of any
aspect of our new Data Flow Info Models?
6.1.5. L2 and L3 Integration
A DetNet network is intended to integrate between Layer 2 (bridged)
network(s) (e.g. AVB/TSN LAN) and Layer 3 (routed) network(s) (e.g.
using IP-based protocols). Does the attack target L2? L3? Both?
The interaction between the two?
6.1.6. End-to-End Delivery
Packets sent over DetNet are guaranteed not to be dropped by the
network due to congestion. (Packets may however be dropped for
intended reasons, e.g. per security measures). Does the attack
result in packets (which should be delivered) not being delivered?
Does it result in packets that should not be delivered being
delivered?
6.1.7. Proprietary Deterministic Ethernet Networks
There are many proprietary non-interoperable deterministic Ethernet-
based networks currently available; DetNet is intended to provide an
open-standards-based alternative to such networks. Does the threat
relate to a specific such network that is being "emulated" or
"replaced" by DetNet, for example by exploiting specific commands
specific to that network protocol?
6.1.8. Replacement for Proprietary Fieldbuses
There are many proprietary "field buses" used in today's industrial
and other industries; DetNet is intended to provide an open-
standards-based alternative to such buses. Does the threat relate to
a specific fieldbus that is being "emulated" or "replaced" by DetNet,
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for example by exploiting specific commands specific to that network
protocol?
6.1.9. Deterministic vs Best-Effort Traffic
DetNet is intended to support coexistence of time-sensitive
operational (OT, deterministic) traffic and information (IT, "best
effort") traffic on the same ("unified") network. Does the attack
affect only IT or only OT or both types of traffic? Does the threat
affect any interaction between IT and OT traffic, e.g. by changing
relative priority or handling of IT vs. OT packets?
6.1.10. Deterministic Flows
Reserved bandwidth data flows (deterministic flows) must be isolated
from each other and from best-effort traffic, so that even if the
network is saturated with best-effort and/or reserved bandwidth
traffic the configured flows are not adversely affected. Does the
attack affect the isolation of one (reserved) flow from another?
6.1.11. Unused Reserved Bandwidth
If bandwidth reservations are made for a stream but the associated
bandwidth is not used at any point in time, that bandwidth is made
available on the network for best-effort traffic. If the owner of
the reserved stream then starts transmitting again, the bandwidth is
no longer available for best-effort traffic, on a moment-to-moment
basis. (Such "temporarily available" bandwidth is not available for
time-sensitive traffic, which must have its own reservation). Does
the attack affect the system's ability to allocate unused reserved BW
to best-effort traffic?
6.1.12. Interoperability
The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus
promoting device diversity and potentially higher numbers of each
device manufactured. Does the threat take advantage of differences
in implementation of "interoperable" products made by different
vendors?
6.1.13. Cost Reductions
The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus
promoting higher numbers of each device manufactured, promoting cost
reduction and cost competition among vendors. Does the threat take
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advantage of "low cost" HW or SW components or other "cost-related
shortcuts" that might be present in devices?
6.1.14. Insufficiently Secure Devices
The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus
promoting device diversity and potentially higher numbers of each
device manufactured. Does the threat attack "naivete" of SW, for
example SW that was not designed to be sufficiently secure (or secure
at all) but is deployed on a DetNet network that is intended to be
highly secure? (For example IoT exploits like the Mirai video-camera
botnet ([MIRAI]).
6.1.15. DetNet Network Size
DetNet networks range in size from very small, e.g. inside a single
industrial machine, to very large, for example a Utility Grid network
spanning a whole country, and involving many "hops" over various
kinds of links for example radio repeaters, microwave links, fiber
optic links, etc.. Does the attack affect DetNet networks of only
certain sizes, e.g. very large networks, or very small? This might
be related to how the attack is introduced into the network, for
example if the entire network is local, there is a threat that power
can be cut to the entire network. If the network is large, perhaps
only a part of the network is attacked. Does the threat take
advantage of attack vectors that are specific to network size?
6.1.16. Multiple Hops
DetNet networks range in size from very small, e.g. inside a single
industrial machine, to very large, for example a Utility Grid network
spanning a whole country, and involving many "hops" over various
kinds of links for example radio repeaters, microwave links, fiber
optic links, etc.. Does the attack exploit the presence of more than
one "hop"? Does the threat exploit the presence of more than one
type of "hop", e.g. between radio and microwave links? Does the
threat exploit a specific type of "hop", e.g. something specific to
a fiber optic link, or other type of link?
6.1.17. Level of Service
A DetNet is expected to provide means to configure the network that
include querying network path latency, requesting bounded latency for
a given stream, requesting worst case maximum and/or minimum latency
for a given path or stream, and so on. It is an expected case that
the network cannot provide a given requested service level. In such
cases the network control system should reply that the requested
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service level is not available (as opposed to accepting the parameter
but then not delivering the desired behavior). Does the attack
affect any querying or replying to such service-level-related
traffic? Can the attack cause incorrect responses from the system
regarding timing-related configuration? For example replying that a
requested level of service is available when it isn't, or that the
requested level of service is not available when it actually is
available?
6.1.18. Bounded Latency
Does the threat affect the network's ability to deliver packets
within the agreed-upon latency boundaries?
6.1.19. Low Latency
Applications may require "extremely low latency" however depending on
the application these may mean very different latency values; for
example "low latency" across a Utility grid network is on a different
time scale than "low latency" in a motor control loop in a small
machine. The intent is that the mechanisms for specifying desired
latency include wide ranges, and that architecturally there is
nothing to prevent arbitrarily low latencies from being implemented
in a given network. Does the threat affect the network's ability to
deliver packets within the agreed-upon low latency?
6.1.20. Symmetrical Path Delays
Some applications would like to specify that the transit delay time
values be equal for both the transmit and return paths. Does the
attack affect the network's ability to provide matched transmit and
return path delays (latencies)?
6.1.21. Reliability and Availability
DetNet based systems are expected to be implemented with essentially
arbitrarily high availability (for example 99.9999% up time, or even
12 nines). The intent is that the DetNet designs should not make any
assumptions about the level of reliability and availability that may
be required of a given system, and should define parameters for
communicating these kinds of metrics within the network. Does the
attack affect the reliability of the DetNet network? Is it a large
or small change, e.g. the difference between completely taking down
the network for some period of time, vs reducing its reliability by
just one "nine"? Does the threat affect the availability of the
DetNet network?
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6.1.22. Redundant Paths
DetNet based systems are expected to be implemented with essentially
arbitrarily high reliability/availability. A strategy used by DetNet
for providing such extraordinarily high levels of reliability is to
provide redundant paths that can be seamlessly switched between, all
the while maintaining the required performance of that system. Does
the attack affect the configuration or operation of redundant paths?
6.1.23. Security Measures
A DetNet network must be made secure against devices failures,
attackers, misbehaving devices, and so on. Does the threat affect
such security measures themselves, e.g. by attacking SW designed to
protect against device failure?
6.2. Attack Types by Use Case Common Theme
The following table lists the attacks of Section 3, assigning a
number to each type of attack. That number is then used as a short
form identifier for the attack in Figure 5.
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+--+----------------------------------------+----------------------+
| | Attack | Section |
+--+----------------------------------------+----------------------+
| 1|Delay Attack | Section 3.2.1 |
+--+----------------------------------------+----------------------+
| 2|DetNet Flow Modification or Spoofing | Section 3.2.2 |
+--+----------------------------------------+----------------------+
| 3|Inter-Segment Attack | Section 3.2.3 |
+--+----------------------------------------+----------------------+
| 4|Replication: Increased attack surface | Section 3.2.4.1 |
+--+----------------------------------------+----------------------+
| 5|Replication-related Header Manipulation | Section 3.2.4.2 |
+--+----------------------------------------+----------------------+
| 6|Path Manipulation | Section 3.2.5.1 |
+--+----------------------------------------+----------------------+
| 7|Path Choice: Increased Attack Surface | Section 3.2.5.2 |
+--+----------------------------------------+----------------------+
| 8|Control or Signaling Packet Modification| Section 3.2.6.1 |
+--+----------------------------------------+----------------------+
| 9|Control or Signaling Packet Injection | Section 3.2.6.2 |
+--+----------------------------------------+----------------------+
|10|Reconnaissance | Section 3.2.7 |
+--+----------------------------------------+----------------------+
|11|Attacks on Time Sync Mechanisms | Section 3.2.8 |
+--+----------------------------------------+----------------------+
Figure 4: List of Attacks
The following table maps the use case themes presented in this memo
to the attacks of Figure 4. Each row specifies a theme, and the
attacks relevant to this theme are marked with a '+'.
+----------------------------+--------------------------------+
| Theme | Attack |
| +--+--+--+--+--+--+--+--+--+--+--+
| | 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Network Layer - AVB/TSN Eth.| +| +| +| +| +| +| +| +| +| +| +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Central Administration | | | | | | +| +| +| +| +| +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Hot Swap | | +| +| | | | | | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Data Flow Information Models| | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|L2 and L3 Integration | | | | | +| +| | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
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|End-to-end Delivery | | | | +| +| | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Proprietary Deterministic | | | +| | | +| +| +| +| | |
|Ethernet Networks | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Replacement for Proprietary | | | +| | | +| +| +| +| | |
|Fieldbuses | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Deterministic vs. Best- | | | +| | | | | | | | |
|Effort Traffic | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Deterministic Flows | | | +| | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Unused Reserved Bandwidth | | | +| | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Interoperability | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Cost Reductions | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Insufficiently Secure | | | | | | | | | | | |
|Devices | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|DetNet Network Size | +| | | | | +| +| | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Multiple Hops | +| +| | | | +| +| | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Level of Service | | | | | | | | +| +| +| |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Bounded Latency | +| | | | | | | | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Low Latency | +| | | | | | | | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Symmetric Path Delays | +| | | | | | | | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Reliability and Availability| +| +| +| +| +| +| +| +| +| +| +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Redundant Paths | | | | +| +| | | +| +| | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Security Measures | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+
Figure 5: Mapping Between Themes and Attacks
7. Appendix A: DetNet Draft Security-Related Statements
This section collects the various statements in the currently
existing DetNet Working Group drafts. For each draft, the section
name and number of the quoted section is shown. The text shown here
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is the work of the original draft authors, quoted verbatim from the
drafts. The intention is to explicitly quote all relevant text, not
to summarize it.
7.1. Architecture (draft 8)
7.1.1. Fault Mitigation (sec 4.5)
One key to building robust real-time systems is to reduce the
infinite variety of possible failures to a number that can be
analyzed with reasonable confidence. DetNet aids in the process by
providing filters and policers to detect DetNet packets received on
the wrong interface, or at the wrong time, or in too great a volume,
and to then take actions such as discarding the offending packet,
shutting down the offending DetNet flow, or shutting down the
offending interface.
It is also essential that filters and service remarking be employed
at the network edge to prevent non-DetNet packets from being mistaken
for DetNet packets, and thus impinging on the resources allocated to
DetNet packets.
There exist techniques, at present and/or in various stages of
standardization, that can perform these fault mitigation tasks that
deliver a high probability that misbehaving systems will have zero
impact on well-behaved DetNet flows, except of course, for the
receiving interface(s) immediately downstream of the misbehaving
device. Examples of such techniques include traffic policing
functions (e.g. [RFC2475]) and separating flows into per-flow rate-
limited queues.
7.1.2. Security Considerations (sec 7)
Security in the context of Deterministic Networking has an added
dimension; the time of delivery of a packet can be just as important
as the contents of the packet, itself. A man-in-the-middle attack,
for example, can impose, and then systematically adjust, additional
delays into a link, and thus disrupt or subvert a real-time
application without having to crack any encryption methods employed.
See [RFC7384] for an exploration of this issue in a related context.
Furthermore, in a control system where millions of dollars of
equipment, or even human lives, can be lost if the DetNet QoS is not
delivered, one must consider not only simple equipment failures,
where the box or wire instantly becomes perfectly silent, but bizarre
errors such as can be caused by software failures. Because there is
essential no limit to the kinds of failures that can occur,
protecting against realistic equipment failures is indistinguishable,
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in most cases, from protecting against malicious behavior, whether
accidental or intentional.
Security must cover:
o Protection of the signaling protocol
o Authentication and authorization of the controlling nodes
o Identification and shaping of the flows
7.2. Data Plane Alternatives (draft 4)
7.2.1. Security Considerations (sec 7)
This document does not add any new security considerations beyond
what the referenced technologies already have.
7.3. Problem Statement (draft 5)
7.3.1. Security Considerations (sec 5)
Security in the context of Deterministic Networking has an added
dimension; the time of delivery of a packet can be just as important
as the contents of the packet, itself. A man-in-the-middle attack,
for example, can impose, and then systematically adjust, additional
delays into a link, and thus disrupt or subvert a real-time
application without having to crack any encryption methods employed.
See [RFC7384] for an exploration of this issue in a related context.
Typical control networks today rely on complete physical isolation to
prevent rogue access to network resources. DetNet enables the
virtualization of those networks over a converged IT/OT
infrastructure. Doing so, DetNet introduces an additional risk that
flows interact and interfere with one another as they share physical
resources such as Ethernet trunks and radio spectrum. The
requirement is that there is no possible data leak from and into a
deterministic flow, and in a more general fashion there is no
possible influence whatsoever from the outside on a deterministic
flow. The expectation is that physical resources are effectively
associated with a given flow at a given point of time. In that
model, Time Sharing of physical resources becomes transparent to the
individual flows which have no clue whether the resources are used by
other flows at other times.
Security must cover:
o Protection of the signaling protocol
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o Authentication and authorization of the controlling nodes
o Identification and shaping of the flows
o Isolation of flows from leakage and other influences from any
activity sharing physical resources
7.4. Use Cases (draft 11)
7.4.1. (Utility Networks) Security Current Practices and Limitations
(sec 3.2.1)
Grid monitoring and control devices are already targets for cyber
attacks, and legacy telecommunications protocols have many intrinsic
network-related vulnerabilities. For example, DNP3, Modbus,
PROFIBUS/PROFINET, and other protocols are designed around a common
paradigm of request and respond. Each protocol is designed for a
master device such as an HMI (Human Machine Interface) system to send
commands to subordinate slave devices to retrieve data (reading
inputs) or control (writing to outputs). Because many of these
protocols lack authentication, encryption, or other basic security
measures, they are prone to network-based attacks, allowing a
malicious actor or attacker to utilize the request-and-respond system
as a mechanism for command-and-control like functionality. Specific
security concerns common to most industrial control, including
utility telecommunication protocols include the following:
o Network or transport errors (e.g. malformed packets or excessive
latency) can cause protocol failure.
o Protocol commands may be available that are capable of forcing
slave devices into inoperable states, including powering-off
devices, forcing them into a listen-only state, disabling
alarming.
o Protocol commands may be available that are capable of restarting
communications and otherwise interrupting processes.
o Protocol commands may be available that are capable of clearing,
erasing, or resetting diagnostic information such as counters and
diagnostic registers.
o Protocol commands may be available that are capable of requesting
sensitive information about the controllers, their configurations,
or other need-to-know information.
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o Most protocols are application layer protocols transported over
TCP; therefore it is easy to transport commands over non-standard
ports or inject commands into authorized traffic flows.
o Protocol commands may be available that are capable of
broadcasting messages to many devices at once (i.e. a potential
DoS).
o Protocol commands may be available to query the device network to
obtain defined points and their values (i.e. a configuration
scan).
o Protocol commands may be available that will list all available
function codes (i.e. a function scan).
o These inherent vulnerabilities, along with increasing connectivity
between IT an OT networks, make network-based attacks very
feasible.
o Simple injection of malicious protocol commands provides control
over the target process. Altering legitimate protocol traffic can
also alter information about a process and disrupt the legitimate
controls that are in place over that process. A man-in-the-middle
attack could provide both control over a process and
misrepresentation of data back to operator consoles.
7.4.2. (Utility Networks) Security Trends in Utility Networks (sec
3.3.3)
Although advanced telecommunications networks can assist in
transforming the energy industry by playing a critical role in
maintaining high levels of reliability, performance, and
manageability, they also introduce the need for an integrated
security infrastructure. Many of the technologies being deployed to
support smart grid projects such as smart meters and sensors can
increase the vulnerability of the grid to attack. Top security
concerns for utilities migrating to an intelligent smart grid
telecommunications platform center on the following trends:
o Integration of distributed energy resources
o Proliferation of digital devices to enable management, automation,
protection, and control
o Regulatory mandates to comply with standards for critical
infrastructure protection
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o Migration to new systems for outage management, distribution
automation, condition-based maintenance, load forecasting, and
smart metering
o Demand for new levels of customer service and energy management
This development of a diverse set of networks to support the
integration of microgrids, open-access energy competition, and the
use of network-controlled devices is driving the need for a converged
security infrastructure for all participants in the smart grid,
including utilities, energy service providers, large commercial and
industrial, as well as residential customers. Securing the assets of
electric power delivery systems (from the control center to the
substation, to the feeders and down to customer meters) requires an
end-to-end security infrastructure that protects the myriad of
telecommunications assets used to operate, monitor, and control power
flow and measurement.
"Cyber security" refers to all the security issues in automation and
telecommunications that affect any functions related to the operation
of the electric power systems. Specifically, it involves the
concepts of:
o Integrity : data cannot be altered undetectably
o Authenticity : the telecommunications parties involved must be
validated as genuine
o Authorization : only requests and commands from the authorized
users can be accepted by the system
o Confidentiality : data must not be accessible to any
unauthenticated users
When designing and deploying new smart grid devices and
telecommunications systems, it is imperative to understand the
various impacts of these new components under a variety of attack
situations on the power grid. Consequences of a cyber attack on the
grid telecommunications network can be catastrophic. This is why
security for smart grid is not just an ad hoc feature or product,
it's a complete framework integrating both physical and Cyber
security requirements and covering the entire smart grid networks
from generation to distribution. Security has therefore become one
of the main foundations of the utility telecom network architecture
and must be considered at every layer with a defense-in-depth
approach. Migrating to IP based protocols is key to address these
challenges for two reasons:
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o IP enables a rich set of features and capabilities to enhance the
security posture
o IP is based on open standards, which allows interoperability
between different vendors and products, driving down the costs
associated with implementing security solutions in OT networks.
Securing OT (Operation technology) telecommunications over packet-
switched IP networks follow the same principles that are foundational
for securing the IT infrastructure, i.e., consideration must be given
to enforcing electronic access control for both person-to-machine and
machine-to-machine communications, and providing the appropriate
levels of data privacy, device and platform integrity, and threat
detection and mitigation.
7.4.3. (BAS) Security Considerations (sec 4.2.4)
When BAS field networks were developed it was assumed that the field
networks would always be physically isolated from external networks
and therefore security was not a concern. In today's world many BASs
are managed remotely and are thus connected to shared IP networks and
so security is definitely a concern, yet security features are not
available in the majority of BAS field network deployments .
The management network, being an IP-based network, has the protocols
available to enable network security, but in practice many BAS
systems do not implement even the available security features such as
device authentication or encryption for data in transit.
7.4.4. (6TiSCH) Security Considerations (sec 5.3.3)
On top of the classical requirements for protection of control
signaling, it must be noted that 6TiSCH networks operate on limited
resources that can be depleted rapidly in a DoS attack on the system,
for instance by placing a rogue device in the network, or by
obtaining management control and setting up unexpected additional
paths.
7.4.5. (Cellular radio) Security Considerations (sec 6.1.5)
Establishing time-sensitive streams in the network entails reserving
networking resources for long periods of time. It is important that
these reservation requests be authenticated to prevent malicious
reservation attempts from hostile nodes (or accidental
misconfiguration). This is particularly important in the case where
the reservation requests span administrative domains. Furthermore,
the reservation information itself should be digitally signed to
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reduce the risk of a legitimate node pushing a stale or hostile
configuration into another networking node.
Note: This is considered important for the security policy of the
network, but does not affect the core DetNet architecture and design.
7.4.6. (Industrial M2M) Communication Today (sec 7.2)
Industrial network scenarios require advanced security solutions.
Many of the current industrial production networks are physically
separated. Preventing critical flows from be leaked outside a domain
is handled today by filtering policies that are typically enforced in
firewalls.
8. IANA Considerations
This memo includes no requests from IANA.
9. Security Considerations
The security considerations of DetNet networks are presented
throughout this document.
10. Informative References
[ARINC664P7]
ARINC, "ARINC 664 Aircraft Data Network, Part 7, Avionics
Full-Duplex Switched Ethernet Network", 2009.
[I-D.ietf-detnet-architecture]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-01 (work in progress), March 2017.
[I-D.ietf-detnet-use-cases]
Grossman, E., Gunther, C., Thubert, P., Wetterwald, P.,
Raymond, J., Korhonen, J., Kaneko, Y., Das, S., Zha, Y.,
Varga, B., Farkas, J., Goetz, F., Schmitt, J., Vilajosana,
X., Mahmoodi, T., Spirou, S., and P. Vizarreta,
"Deterministic Networking Use Cases", draft-ietf-detnet-
use-cases-12 (work in progress), April 2017.
[I-D.varga-detnet-service-model]
Varga, B. and J. Farkas, "DetNet Service Model", draft-
varga-detnet-service-model-02 (work in progress), May
2017.
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[IEEE1588]
IEEE, "IEEE 1588 Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems Version 2", 2008.
[MIRAI] krebsonsecurity.com, "https://krebsonsecurity.com/2016/10/
hacked-cameras-dvrs-powered-todays-massive-internet-
outage/", 2016.
[RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
October 2014, <http://www.rfc-editor.org/info/rfc7384>.
Authors' Addresses
Tal Mizrahi
Marvell
Email: talmi@marvell.com
Ethan Grossman (editor)
Dolby Laboratories, Inc.
1275 Market Street
San Francisco, CA 94103
USA
Phone: +1 415 645 4726
Email: ethan.grossman@dolby.com
URI: http://www.dolby.com
Andrew J. Hacker
MistIQ Technologies, Inc
Harrisburg, PA
USA
Email: ajhacker@mistiqtech.com
URI: http://www.mistiqtech.com
Subir Das
Applied Communication Sciences
150 Mount Airy Road, Basking Ridge
New Jersey, 07920
USA
Email: sdas@appcomsci.com
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John Dowdell
Airbus Defence and Space
Celtic Springs
Newport NP10 8FZ
United Kingdom
Email: john.dowdell.ietf@gmail.com
Henrik Austad
Cisco Systems
Philip Pedersens vei 1
Lysaker 1366
Norway
Email: henrik@austad.us
Kevin Stanton
Intel
Email: kevin.b.stanton@intel.com
Norman Finn
Huawei
Email: norman.finn@mail01.huawei.com
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