Internet DRAFT - draft-macaulay-6man-packet-stain
draft-macaulay-6man-packet-stain
6man Working Group T. Macaulay
Internet-Draft McAfee Inc.
Intended status: Standards Track Aug 2012
Expires: February 2, 2013
IPv6 packet staining
draft-macaulay-6man-packet-stain-01
Abstract
This document specifies the application of security staining on an
IPv6 datagrams and the minimum requirements for IPv6 nodes staining
flows, IPv6 nodes forwarding stained packets within a given domain of
control, and nodes interpreting stains on flows.
The usage of the packet staining destination option enables proactive
delivery of security intelligence to IPv6 nodes such as firewalls and
intrusion prevention systems, and end-points such servers,
workstations, mobile and smart devices and an infinite array of as-
yet-to-be-invented sensors and controllers.
The usage of packet staining is not intended for use across the open
internet, where fragmentation issues associated with increased header
size may induce service degradation; packet staining is intended as a
security adjunct within a given doamin of control such as an carrier
or enterprise network.
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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This Internet-Draft will expire on February 2, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Packet Staining Benefits . . . . . . . . . . . . . . . . . 4
3.2. Implementation and support models . . . . . . . . . . . . 5
3.3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Requirements for staining IPv6 packets . . . . . . . . . . . . 7
5. Packet Stain Destination Option (PSDO) . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
From the viewpoint of the network layer, a flow is a sequence of
packets sent from a particular source to a particular unicast,
anycast, or multicast destination. From an upper layer viewpoint, a
flow could consist of all packets in one direction of a specific
transport connection or media stream. However, a flow is not
necessarily 1:1 mapped to a transport connection.
Traditionally, flow classifiers have been based on the 5-tuple of the
source and destination addresses, ports, and the transport protocol
type. However, as the growth of internetworked devices continues
under IPv6, security issues associated with the reputation of the
source of flows are becoming a critical criterion associated with the
trust of the data payloads and the security of the destination end-
points and the networks on which they reside.
The usage of security reputational intelligence associated with the
source address field and possibly the port and protocol [REF1]
enables packet-by-packet IPv6 security classification, where the IPv6
header extensions in the form of Destination Options may be used to
stain each packet with security reputation information such that the
network routing is unaffected, but intermediate security nodes and
endpoint devices can apply policy decisions about incoming
information flows without the requirement to assemble and treat
payloads at higher levels of the stack.
IPv6 packet staining support consists of labeling datagrams with
security reputation information through the addition of an IPv6
destination option in the packet header by packet manipulation
devices (PMDs) in the carrier or enterprise network. This
destination option may be read by in-line security nodes upstream
from the packet destination, as well as by the destination nodes
themselves.
The usage of packet staining is not intended for use across the open
internet, where fragmentation issues associated with increased header
size may induce service degradation; packet staining is intended as a
security adjunct within a given doamin of control such as an carrier
or enterprise network.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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3. Background
Internet based threats in the form of both malicious software and the
agents that control this software (organized crime, spys,
hackitivits) have surpassed the abilities of signature-based security
systems; whether they be on the enterprise perimeter, within the
corporate network, on the endpoint point or in-the-cloud (internet-
based service). Additionally, the sensitivity of IP network
continues to grow as new generation of smart devices is appearing on
the networks in the form of broadband mobile devices, legacy
industrial control devices, and very low-power sensors. This diverse
collections of IP-based assets is coming to be known as the Internet
of Things (IOT).
In response to the accelerating threats, the security vendor
community have integrated their products with proprietary forms of
security reputation intelligence. This intelligence is about IP
addresses and domains which have been observed engaged in attack-
behaviours such as inappropriate messaging and traffic volumes,
domain management, Botnet command-and-control channel exchanges and
other indicators of either compromise or malicious intent. [REF 1]
IP address may also end up on a security reputation list if they are
identified as compromised through vendor-specific signature-based
processes. Security reputation intelligence from vendors is
typically made available to perimeter and end-point products through
proprietary, internet-based queries to vendor information bases.
This system of using proactive, security reputation intelligence has
many benefits, but also several weakness and scaling challenges.
Specifically, existing intelligence systems are:
1. subject to direct attack from the internet on distribution
points, for instance
2. are proprietary to vendor devices
3. require fat-clients consuming both bandwidth and CPU, and
4. introduces flow latency while queries are sent, received and
processed
5. introduces intelligence latency as reputation lists will be
inevitably cached and only periodically refreshed given the
number and range of vendor-specific processing elements
3.1. Packet Staining Benefits
In contrast to the challenges of current security reputation
intelligence systems, packet staining has the following strengths
1. packet staining can occur transparently in the network,
presenting no attack surface
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2. packet staining uses standardized, public domain IPv6
capabilities
3. security rules can be easily applied in hardware or firmware
4. reading packet stains introduces little to no latency
5. near-real-time threat intelligence distribution systems can be
implemented can be implemented out of band in PMDs using a
standardized packet staining method allowing multiple
intelligence sources (vendor sources) to be aggregated and
applied in an agnostic (cross-vendor) manner.
3.2. Implementation and support models
Packet staining may be accomplished by different entities including
carriers, enterprises and third-party value-added service providers.
Carriers or service providers may elect to implement staining centres
at strategic locations in the network to provide value-added services
on a subscription basis. Under this model, subscribers to a security
staining service would see their traffic directed through a staining
centre where Destination Options are added to the IPv6 headers and
IPv4 traffic is encapsulated within IPv6 tunnels, with stained
headers.
Carriers or service providers may elect to stain all IPv6 traffic
entering their network, and allow subscribers to process the stains
at their own discretion.
If such upstream, network-based staining services are inappropriate
or unavailable, Enterprise data centre managers / cloud computing
service providers may elect to deploy IPv6 staining at the perimeter
into the internal network, tunnelling all IPv4 traffic, and allow
data centre/cloud service users to process stains at their
discretion.
Enterprise may wish to deploy IPv6 on internal networks, and stain
all internal traffic whereby security nodes and end-points may apply
corporate security policy related to reputation.
3.3. Use cases
The following are example use-cases for a security technique based
upon a packet staining system.
Organization Perimeter Use-case Traffic to a subscriber is routed
through a PMD in the carrier network configured to stain (apply
Destination Options extensions) all packets to the subscriber (TM)s
IP-range, which have entries in the threat intelligence information
base. The PMD accesses the information base from a locally cached
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file or other method not defined in this draft. Packets from sources
not in the information base pass through the PDM unchanged. Packets
from sources in the information base have a Destinations Option added
to the datagram header. The Destination Options contains reputation
from the information base. The format of the destination option is
discussed later in this draft. IPv6 perimeter devices such as
firewalls, web proxies or security routers on the perimeter of the
subscriber network look for Destination Options on incoming packets
with reputation stains. If a stain is found, the perimeter device
applies the organization policy associated with the reputation
indicated by the stain. For instance, drop the packet, quarantine
the packet, issue alarms, or pass the packets and associated flow to
specially hardened extra-net authentication systems, or do nothing.
IPv4 support Use-case" IPv4 header fields and options are not
suitable for packet staining; however, there is a clear security
benefit to supporting IPv4 flows. IPv4 traffic to a subscriber is
routed through a PMD in the carrier network configured to encapsulate
the IPv4 traffic in an IPv6 tunnel. The PMD applies a stain
(Destination Options extension) to the IPv6 tunnel as per the
Perimeter Use-case above. Subscriber perimeter devices such as
firewalls, web proxies or security routers are configured to support
both native IPv6 flows and IPv6 tunnels contain legacy IPv4 flows.
Perimeter devices look for Destination Options on incoming IPv6
packets with reputation stains. If a stain is found, the perimeter
device applies the organization policy associated with the reputation
indicated by the stain to the IPv4 packet within the IPv6 tunnel. In
this manner IPv4 support may be transparent to end-users and
applications.
IPv6 end-point use-case" IPv6 end-points may make use of reputation
stains by processing Destination Options before engaging in any
application level processing. In the case of certain classes of
smart device, remote and mobile sensors, reputation stains may be a
critical form of security when other mitigations such as signature
bases and firewalls are too power and processor intensive to support.
URL-specific stains" it is a common occurrence to see large public
content portals with millions of users sharing dozens of addresses.
Frequently, malicious content will be loaded to such sites. This
content represents a very small fraction of the otherwise legitimate
content on the site, which may be under the direct control of
entirely separate entities . Degrading the reputation of IP
addresses used by these large portals based on a very small amount of
content is problematic. For such sites, reputation stains should
have the ability to include the URL of malicious content, such that
the reputation of the only specific portions of these large portals
is degraded according to threat evidence, rather than the entire IP
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address, CIDR block, ASN or domain name.
4. Requirements for staining IPv6 packets
1. The default behaviour of a security node MUST be to leave a
packet unchanged (apply no stain).
2. Reputation stains may be inserted or overwritten by security
nodes in the path.
3. Reputation stains may not be applied by the sender/source of the
packet.
4. The reputation staining mechanism needs to be visible to all
stain-aware nodes on the path.
5. The mechanism needs to be able to traverse nodes that do not
understand the reputation stains. This is required to ensure
that packet-staining can be incrementally deployed over the
Internet.
6. The presence of the reputation staining mechanism should not
significantly alter the processing of the packet by nodes, unless
policy is explicitly configured. This is required to ensure that
stained packets do not face any undue delays or drops due to a
badly chosen mechanism.
7. A PMD should be able to distinguish a trusted stain from an
untrusted stain, through mechanism such as digital signatures or
intrinsic trust among network elements.
8. A staining node MAY apply more specific and selective staining
services according to subscriptions. Staining nodes SHOULD
support different reputation taxonomies to support different
subscribers and/or interoperability with other staining entities,
and have the ability to stain flows to different subscriber
sources according to different semantics.
9. Staining MUST NOT increase header size such that headers are
fragmented due to nodes supporting MTU smaller than the complete
header, once stained. Therefore staining should only be applied
within a domain of control where MTU is known and can be managed.
5. Packet Stain Destination Option (PSDO)
The Packet Stain Destination Option (PSDO) is a destination option
that can be included in IPv6 datagrams that are inserted by PMDs in
order to inform packet staining aware nodes on the path, or
endpoints, that the PSDO has an alignment requirement of (none).
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|U| Stain Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Packet Stain Destination Option Layout
Option Type
8-bit identifier of the type of option. The option identifier
for the reputation stain option will be allocated by the IANA.
Option Length
8-bit unsigned integer. The length of the option (excluding
the Option Type and Option Length fields).
S Bit
When this bit is set, the reputation stain option has been signed.
U Bit
When this bit is set, the reputation stain option contains a
malicious URL.
Stain Data
Contains the staining data.
6. Acknowledgements
The author wishes to achknowledge the guidance and support of Suresh
Krishnan from Ericsson's Montreal lab. The author also wishes to
credit Chris Mac-Stoker from NIKSUN for his substantial contributions
to the early stages of the packet staining concept.
7. Security Considerations
Some implementation may elect to no apply digital signature to
reputation stains in the Destination Option, in which case the stain
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is not protected in any way, even if IPsec authentication [RFC4302]
is in use. Therefore an unsigned reputation stain can be forged by
an on-path attacker. Implementers are advised that any en-route
change to an unsigned security reputation stain value is
undetectable. Therefore packet staining use the Destination Options
extension without digital signatures requires intrinsic trust among
the network elements and the PMD, and the destination node or
intervening security nodes such as firewalls or IDS services. For
this reason, receiving nodes MAY need to take account of the network
from which the stained packet was received. For instance, a multi-
homed organization may have some service providers with staining
services and others that do not. A receiving node SHOULD be able to
distinguish which source from which stains are expected. A receiving
node SHOULD by default ignore any reputation stains from sources
(networks or devices) that have not been specifically configured as
trusted.
The reputation intelligence of IP source addresses, ASNs, CIDR blocks
and domains is fundamental to the application of reputation stains
within packet headers. Such reputation information can be seeded
from a variety of open and closed sources. Poorly managed or
compromised intelligence information bases can result in denial of
service against legitimate IP addresses, and allow malicious entities
to appear trustworthy. Intelligence information bases themselves may
be compromised in a variety of ways; for instance the raw information
feeds may be corrupted with erroneous information, alternately the
intelligence reputation algorithms could be flawed in design or
corrupted such that they generate false reputation scores. Therefore
seed intelligence SHOULD be sourced and monitored with demonstratable
diligence. Similarly, reputation algorithms should be protected from
unauthorized change with multi-layered access controls.
The value of reputation stains will be directly proportional to the
trustworthiness, reliability and reputation of the intelligence
source itself. Operators of security nodes SHOULD have defined and
auditable methods upon which they select and manage the source of
reputation intelligence and the packet staining infrastructure
itself.
8. IANA Considerations
This document defines a new IPv6 destination option for carrying
security reputation packet stains. IANA is requested to assign a new
destination option type (TBA1) in the Destination Options registry
maintained at http://www.iana.org/assignments/ipv6-parameters 1)
Signed Security Reputation Option, 2) Unsigned Security Reputation
Option 3) Signed Security Reputation Option with malicious URL 4)
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Unsigned Security Reputation Option with malicious URL The act bits
for this option need to be 10 and the chg bit needs to be 0.
9. Normative References
[REF1] Macaulay, T., "Upstream Intelligence: anatomy,
architecture, case studies and use-cases.", Information
Assurance Newsletter, DOD , Aug to Feburary 2010 to 2011.
[REF2] Gont, F., "Security and Interoperability of Oversized IPv6
Header Chains", June 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
Author's Address
Tyson Macaulay
McAfee Inc.
2821 Mission College Boulevard
Sanata Clara, California
U.S.A.
Email: tyson_macaulay@mcafee.com
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