Network Working Group A. Barbir
Internet-Draft Nortel Networks
Expires: August 11, 2003 O. Batuner
Independent consultant
B. Srinivas
Nokia
M. Hofmann
Bell Labs/Lucent Technologies
H. Orman
Purple Streak Development
February 10, 2003
Security Threats and Risks for OPES
draft-ietf-opes-threats-02
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
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."
The list of current Internet-Drafts can be accessed at http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 11, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
The document investigates the security threats associated with OPES.
The effects of security threats on the underlying architecture are
discussed. The main goal of this document is threat discovery and
analysis. The document does not specify or recommend any solutions.
Barbir, et al. Expires August 11, 2003 [Page 1]
Internet-Draft Security Threats and Risks for OPES February 2003
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3
2. OPES Data Flow Threats . . . . . . . . . . . . . . . . . . 5
2.1 OPES Flow Network Level Threats . . . . . . . . . . . . . 6
2.1.1 Connection-Flow Denial-of-Service (DoS) . . . . . . . . . 6
2.1.2 Threats to network robustness . . . . . . . . . . . . . . 7
2.2 OPES Flow Application Level Threats . . . . . . . . . . . 7
2.2.1 Unauthorized OPES entities . . . . . . . . . . . . . . . . 7
2.2.2 Unauthorized actions of legitimate OPES entities . . . . . 7
2.2.3 Unwanted content transformations . . . . . . . . . . . . . 8
2.2.4 Corrupted content . . . . . . . . . . . . . . . . . . . . 8
2.2.5 Threats to message structure integrity . . . . . . . . . . 8
2.2.6 Granularity of protection . . . . . . . . . . . . . . . . 9
2.2.7 Risks of hop-by-hop protection . . . . . . . . . . . . . . 9
2.2.8 Threats to integrity of complex data . . . . . . . . . . . 10
2.2.9 Denial of Service (DoS) . . . . . . . . . . . . . . . . . 10
2.2.10 Tracing and notification information . . . . . . . . . . . 10
2.2.11 Unauthenticated Communication in OPES Flow . . . . . . . . 10
3. Threats to out-of-band data . . . . . . . . . . . . . . . 11
3.1 Threats that endanger the OPES data flow . . . . . . . . . 11
3.2 Inaccurate Accounting Information . . . . . . . . . . . . 11
3.3 OPES service request repudiation . . . . . . . . . . . . . 12
3.4 Inconsistent privacy policy . . . . . . . . . . . . . . . 12
3.5 Exposure of privacy preferences . . . . . . . . . . . . . 12
3.6 Exposure of security settings . . . . . . . . . . . . . . 12
3.7 Improper enforcement of privacy and security policy . . . 13
3.8 DOS Attacks . . . . . . . . . . . . . . . . . . . . . . . 13
4. Security Considerations . . . . . . . . . . . . . . . . . 14
Normative References . . . . . . . . . . . . . . . . . . . 15
Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 16
A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . 19
Barbir, et al. Expires August 11, 2003 [Page 2]
Internet-Draft Security Threats and Risks for OPES February 2003
1. Introduction
The Open Pluggable Edge Services (OPES) [1] architecture enables
cooperative application services (OPES services) between a data
provider, a data consumer, and zero or more OPES processors. The
application services under consideration analyze and possibly
transform application-level messages exchanged between the data
provider and the data consumer. The OPES processor can distribute
the responsibility of service execution by communicating and
collaborating with one or more remote callout servers. The details of
the OPES architecture can be found in [1].
Security threats with respect to OPES can be viewed from different
angles. There are security risks that affect content consumer
applications, and those that affect the data provider applications.
These threats affect the quality and integrity of data that the
applications either produce or consume. On the other hand, the
security risks can also be categorized into trust within the system
(i.e. OPES service providers) and protection of the system from
threats imposed by outsiders such as hackers and attackers. Insiders
are those parties that are part of the OPES system. Outsiders are
those entities that are not participating in the OPES system.
It must be noted that not everyone in an OPES delivery path is
equally trusted. Each OPES administrative trust domain must protect
itself from all outsiders. Furthermore, it may have limited trust
relationship with another OPES administrative domain for certain
purposes.
OPES service provide must use authentication as the basis for
building trust relationships between administrative domains.
Insiders can intentionally or unintentionally inflict harm and damage
on the data consumer and data provider applications. This can be
through bad system configuration, execution of bad software or, if
their networks are compromised, by inside or outside hackers.
Depending on the deployment scenario, the trust within the OPES
system is based on a set of transitive trust relationships between
the data provider application, the OPES entities and the data
consumer application. Threats to OPES entities can be at the OPES
flow level and/or at the network level.
In considering threats to the OPES system, the document will follow a
threat analysis model that identifies the threats from the
perspective of how they will affect the data consumer and the data
provider applications.
The main goal of this document is threat discovery and analysis. The
Barbir, et al. Expires August 11, 2003 [Page 3]
Internet-Draft Security Threats and Risks for OPES February 2003
document does not specify or recommend any solutions.
It is important to mention that the OPES architecture has many
similarities with other so called overlay networks, specifically web
caches and content delivery networks (CDN) (see [2] , [4] ). This
document focuses on threats that are introduced by the existence of
the OPES processor and callout servers. Security threats specific to
content services that do not use the OPES architecture are considered
out-of-scope of this document. However, this document can be used as
input when considering security implications for web caches and CDNs.
The document is organized as follows: Section 2 discusses threats to
OPES data flow on network and application level, section 3 discusses
threats to other parts of the system and section 4 discusses security
considerations.
Barbir, et al. Expires August 11, 2003 [Page 4]
Internet-Draft Security Threats and Risks for OPES February 2003
2. OPES Data Flow Threats
Threats to OPES data flow can affect the data consumer and data
provider applications. At the OPES flow level, threats can occur at
Policy Enforcement Points and Policy Decision Points [3] and along
the OPES flow path where network elements are used to process the
data.
A serious problem is posed by the very fact that the OPES
architecture is based on widely adopted protocols (HTTP is used as an
example). The architecture document specifically requires that "the
presence of an OPES processor in the data request/response flow SHALL
NOT interfere with the operations of non-OPES aware clients and
servers". This greatly facilitates OPES deployment but on the other
hand a vast majority of clients (browsers) will not be able to
exploit any safeguards added as base protocol extensions.
For the usual data consumer, who might have questions such as (Where
does this content come from? Can I get it another way? What is the
difference? Is it legitimate?). Even if there are facilities and
technical expertise present to pursue these questions, such thorough
examination of each result is prohibitively expensive in terms of
time and effort. OPES-aware content providers may try to protect
themselves by adding verification scripts and special page
structures. OPES-aware end users may use special tools. In all other
cases (non-OPES aware clients and servers) protection will rely on
monitoring services and investigation of occasionally discovered
anomalies.
An OPES system poses a special danger as a possible base for
classical man-in-the-middle attacks. One of the reasons why such
attacks are relatively rare is the difficulty in finding an
appropriate base: a combination of a traffic interception point
controlling a large flow of data and an application codebase running
on a high-performance hardware with sufficient performance to
analyze and possible modify all passing data. An OPES processor meets
this definition. This calls for special attention to protection
measures at all levels of the system.
Any compromise of an OPES processor or remote callout server can have
a ripple effect on the integrity of the affected OPES services across
all service providers that use the service. To mitigate this threat
appropriate security procedures and tools (e.g., a firewall) should
be applied.
Specific threats can exist at the network level and at OPES data flow
level.
Barbir, et al. Expires August 11, 2003 [Page 5]
Internet-Draft Security Threats and Risks for OPES February 2003
2.1 OPES Flow Network Level Threats
OPES processor and callout servers are susceptible to network level
attacks from outsiders or from the networks of other OPES service
providers (i.e. if the network of a contracted OPES service is
compromised).
The OPES architecture is based on common application protocols that
do not provide strong guarantees of privacy, authentication, or
integrity. The IAB considerations [4] require that the IP address of
an OPES processor be accessible to data consumer applications at the
IP addressing level. This requirement limit the ability of service
providers of positioning the OPES processor behind firewalls and may
exposes the OPES processor, including remote callout servers, to
network level attacks. For example, the use of TCP/IP as network
level protocol makes OPES processors subject to many known attacks,
such as IP spoofing and session stealing.
The OPES system is also susceptible to a number of security threats
that are commonly associated with network infrastructure. These
threats include snooping, denial of service, sabotage, vandalism,
industrial espionage and theft of service.
There are best practice solutions to mitigate network level threats.
It is recommended that the security of the OPES entities at the
network level be enhanced using known techniques and methods that
minimize the risks of IP spoofing, snooping, denial of service and
session stealing.
At the OPES Flow level, connection-level security between the OPES
processor and callout servers is an important consideration. For
example, it is possible to spoof the OPES processor or the remote
callout server. There are threats to data confidentiality between the
OPES processor and the remote callout server in an OPES flow.
The next subsections covers possible DOS attack on OPES processor,
remote callout server or data consumer application and network
robustness.
2.1.1 Connection-Flow Denial-of-Service (DoS)
OPES processors, or callout servers or data consumer applications can
be vulnerable to DOS attacks. DOS attacks can be of various types.
One example of DOS attacks is the overloading of OPES processors or
callout servers by spurious service requests issued by a malicious
node, which denies the legal data traffic the necessary resources to
render service. The resources include CPU cycles, memory, network
interfaces, etc. A Denial-of-Service attack can be selective,
Barbir, et al. Expires August 11, 2003 [Page 6]
Internet-Draft Security Threats and Risks for OPES February 2003
generic or random in terms of which communication streams are
affected.
Distributed DoS is also possible when an attacker successfully
directs multiple nodes over the network to initiate spurious service
requests to an OPES processor(or callout server) simultaneously.
2.1.2 Threats to network robustness
If OPES implementation does violate end-to-end addressing principles,
it could endanger the Internet infrastructure by complicating routing
and connection management. If it does not use flow-control
principles for managing connections, or if it interferes with
end-to-end flow control of connections that it did not originate,
then it could cause Internet congestion.
An implementation that violates the IAB requirement of explicit IP
level addressing (for example by adding OPES functional capabilities
to an interception proxy) may defeat some of the protective
mechanisms and safeguards built into the OPES architecture.
2.2 OPES Flow Application Level Threats
At the content level, threats to the OPES system can come from
outsiders or insiders. The threat from outsiders is frequently
intentional. Threats from insiders can be intentional or due to
inappropriate implementations such as programming and configuration
errors that result in bad system behavior.
Application level problems and threats to the OPES systems are
discussed below:
2.2.1 Unauthorized OPES entities
Although one party authorization is mandated by the OPES
architecture, such authorization occurs out-of-band. Discovering the
presence of an OPES entity and verifying authorization requires
special actions and may present a problem.
Adding notification and authorization information to the data
messages (by using base protocol extensions) may help, especially if
the data consumer's software is aware of such extensions.
2.2.2 Unauthorized actions of legitimate OPES entities
According to the OPES architecture, the authorization is not tightly
coupled with specific rules and procedures triggered by the rules.
Even if a requirement to approve each particular rule and procedure
Barbir, et al. Expires August 11, 2003 [Page 7]
Internet-Draft Security Threats and Risks for OPES February 2003
was set, it looks at least impractical if not impossible to request
such permission from the end user. The authorization is basically
given for the class of transformations. The actual rules and
triggered procedures may (maliciously or due to a programming error)
perform actions that they are not authorized for.
2.2.3 Unwanted content transformations
An authorized OPES service may perform actions that do not adhere to
the expectations of the party that gave the authorization for the
service. Examples may include ad flooding by a local ad insertion
service or use of inappropriate policy by a content filtering
service.
On the other hand an OPES entity acting on behalf of one party may
perform transformations that another party deems inappropriate.
Examples may include replacing ads initially inserted by the content
provider or applying filtering transformations that change the
meaning of the text.
2.2.4 Corrupted content
The OPES system may deliver outdated or otherwise distorted
information due to programming problems or as a result of malicious
attacks. For example, a compromised server, instead of performing
OPES service, may inject bogus content. Such an action may be an act
of cyber-vandalism (including virus injection) or intentional
distribution of misleading information (such as manipulations with
financial data).
A compromised OPES server or malicious entity in the data flow may
introduce changes specifically intended to cause improper actions in
the OPES server or callout server. These changes may be in the
message body, headers or both. This type of threat is discussed in
more detail below.
2.2.5 Threats to message structure integrity
An OPES server may add, remove or delete certain headers in a request
and/or response message (for example to implement additional privacy
protection or assist in content filtering). Such changes may violate
end-to-end integrity requirements or defeat services that use
information provided in such headers (for example some local
filtering services or reference-based services).
Barbir, et al. Expires August 11, 2003 [Page 8]
Internet-Draft Security Threats and Risks for OPES February 2003
2.2.6 Granularity of protection
OPES services have implicit permission to modify content. However,
the permissions generally apply only to portions of the content, for
example, URL's between particular HTML tags, or text in headlines, or
URL's matching particular patterns. In order to express such
policies, one must be able to refer to portions of messages and to
detect modifications to message parts.
Because there is currently very little support for policies that are
expressed in terms of message parts, it will be difficult to
attribute any particular modification to a particular OPES processor,
or to automatically detect policy violations.
A fine-grained policy language should be devised, and it could be
enforced using digital signatures. This would avoid the problems
inherent in hop-by-hop data integrity measures (see next section).
2.2.7 Risks of hop-by-hop protection
OPES services cannot be applied to data protected with end-to-end
encryption methods because, by definition, the decryption key cannot
be shared with OPES processors. This means that if the endpoint
policies permit OPES services, the data must either be transmitted
without confidentiality protections or else with an alternative to
end-to-end encryption: hop-by-hop encryption. In the latter case, all
the parties in the OPES processing path must understand the
encryption requirement and negotiate encrypted connections with their
OPES partners.
Hop-by-hop protection is less effective than end-to-end protection,
because any processor in the path which shares a cryptographic key,
can violate the confidentiality or integrity of the data without
detection.
If a pair of processors in the delivery path use weak cryptography or
manage keys poorly, there is a danger of data leakage. For this
reason, different cryptographic keys should be used for each leg of
the data stream.
Even if the data is not confidential, one might desire some checks on
data integrity, to avoid modifications by unauthorized parties. The
comments above apply to the use of end-to-end integrity, if it is
based on shared-key cryptography. Again, it should be possible to
use hop-by-hop data integrity to protect data as it moves between
protection domains.
Currently there is no method to signal hop-by-hop encryption or
Barbir, et al. Expires August 11, 2003 [Page 9]
Internet-Draft Security Threats and Risks for OPES February 2003
integrity requirements. Either this must be added to the application
protocol, or OPES must define its own signaling protocol, or all OPES
traffic MUST ALWAYS be encrypted.
2.2.8 Threats to integrity of complex data
The OPES system may violate data integrity by applying inconsistent
transformations to interrelated data objects or references within the
data object. Problems may range from a broken reference structure
(modified/missing targets, references to wrong locations or missing
documents) to deliberate replacement/deletion/insertion of links that
violate intentions of the content provider.
2.2.9 Denial of Service (DoS)
The data consumer application may not be able to access data if the
OPES system fails for any reason.
A malicious or malfunctioning node may be able to block all traffic.
The data traffic destined for the OPES processor (or callout server)
may not be able to use the services of the OPES device. The DoS may
be achieved by preventing the data traffic from reaching the
processor or the callout server.
2.2.10 Tracing and notification information
Inadequate or vulnerable implementation of the tracing and
notification mechanisms may defeat safeguards built into the OPES
architecture.
Tracing and notification facilities may become a target of malicious
attack. Such an attack may create problems in discovering and
stopping other attacks.
The absence of a standard for tracing and notification information
may present an additional problem. This information is produced and
consumed by the independent entities (OPES servers/user agents/
content provider facilities). This calls for a set of standards
related to each base protocol in use.
2.2.11 Unauthenticated Communication in OPES Flow
There are risks and threats that could arise from unauthenticated
communication between the OPES server and callout servers. Lack of
use of strong authentication between OPES processors and callout
servers may open security holes whereby DOS and other types of
attacks (see sections [2 and 3]) can be performed.
Barbir, et al. Expires August 11, 2003 [Page 10]
Internet-Draft Security Threats and Risks for OPES February 2003
3. Threats to out-of-band data
The OPES architecture separates a data flow from a control
information flow (loading rulesets, trust establishment, tracing,
policy propagation, etc.). There are certain requirements set for
the latter but no specific mechanism is prescribed. This gives more
flexibility for implementations but creates more burden for
implementers and potential customers to ensure that each specific
implementation meets all requirements for data security, entity
authentication and action authorization.
In addition to performing correct actions on the OPES data flow, any
OPES implementation has to provide an adequate mechanism to satisfy
requirements for out-of-band data and signaling information
integrity.
Whatever the specific mechanism may be, it inevitably becomes subject
to multiple security threats and possible attacks. The way the
threats and attacks may be realized depends on implementation
specifics but the resulting harm generally falls into two categories:
threats to OPES data flow and threats to data integrity.
The specific threats are:
3.1 Threats that endanger the OPES data flow
Any weakness in the implementation of a security, authentication, or
authorization mechanism may open the door to the attacks described in
section 2.
An OPES system implementation should address all these threats and
prove its robustness and ability to withstand malicious attacks or
networking and programming problems.
3.2 Inaccurate Accounting Information
Collecting and reporting accurate accounting data may be vital when
OPES servers are used to extend a business model of content provider,
service provider or as a basis for third party service. Ability to
collect and process accounting data is an important part of OPES
system functionality. This functionality may be challenged by
distortion or destruction of base accounting data (usually logs),
processed accounting data, accounting parameters and reporting
configuration.
As a result a data consumer may be inappropriately charged for
viewing content that was not successfully delivered, or a content
provider or independent OPES services provider may not be compensated
Barbir, et al. Expires August 11, 2003 [Page 11]
Internet-Draft Security Threats and Risks for OPES February 2003
for the services performed.
OPES system may use accounting information to distribute resources
between different consumers or limit resource usage by a specific
consumer. In this case an attack on accounting system (by distortion
of data or issuing false configuration commands) may result in
incorrect resource management and DoS by artificial resource
starvation.
3.3 OPES service request repudiation
An entity (producer or consumer) makes an authorized request and
claim, later, that it did not make that request. As a result an OPES
entity may be held liable for unauthorized changes to the data flow,
or will be unable to receive compensation for a service.
There SHOULD be a clear request that this service is required and
there SHOULD be a clear course of action on the behalf of all
parties. This action SHOULD have a request, and SHOULD have an
action, and SHOULD have a means of repudiation of the request, and
SHOULD have a means to specify the effect of the action.
3.4 Inconsistent privacy policy
The OPES entities may have privacy policies that are not consistent
with the data consumer application or content provider application.
Privacy related problems may be further complicated if OPES entities,
content providers and end users belong to different jurisdictions
with different requirements and different levels of legal protection.
As a result the end user may not be aware that he or she does not
have the expected legal protection. The content provider may be
exposed to legal risks due to a failure to comply with regulation
which he is not even aware of.
3.5 Exposure of privacy preferences
The OPES system may inadvertently or maliciously expose end user
privacy settings and requirements.
3.6 Exposure of security settings
There are risks that the OPES system may expose end user security
settings when handling the request and responses. The user data must
be handled as sensitive system information and protected against
accidental and deliberate disclosure.
Barbir, et al. Expires August 11, 2003 [Page 12]
Internet-Draft Security Threats and Risks for OPES February 2003
3.7 Improper enforcement of privacy and security policy
OPES entities are part of the content distribution system and as such
take on certain obligations to support security and privacy policies
mandated by content producer and/or end user. However there is a
danger that these policies are not properly implemented and enforced.
The data consumer application may not be aware that its protections
are no longer in effect.
There is also the possibility of security and privacy leaks due to
the accidental misconfiguration or, due to missunderstanding what
rules are in effect for a particular user or request.
Privacy and security related parts of the systems can be targeted by
malicious attacks and ability to withstand such attacks is of
paramount importance.
3.8 DOS Attacks
DOS attacks can be of various types. One type of DOS attacks can take
effect by overloading the client. For example, an intruder can direct
an OPES processor to issue numerous responses to a client. There is
also additional DOS risk from a rule misconfiguration that would have
the OPES processor ignore a data consumer application.
Barbir, et al. Expires August 11, 2003 [Page 13]
Internet-Draft Security Threats and Risks for OPES February 2003
4. Security Considerations
This document discusses multiple security and privacy issues related
to the OPES services.
Barbir, et al. Expires August 11, 2003 [Page 14]
Internet-Draft Security Threats and Risks for OPES February 2003
Normative References
[1] A. Barbir et. al, "An Architecture for Open Pluggable Edge
Services (OPES)", Internet-Draft: http://www.ietf.org/
internet-drafts/draft-ietf-opes-architecture-04.txt, Aug 2002.
[2] A. Barbir et. al, "OPES Use Cases and Deployment Scenarios",
Internet-Draft: http://www.ietf.org/
draft-ietf-opes-scenarios-01, July 2002.
[3] A. Barbir et. al, "Requirements for Policy, Authorization and
Enforcement of OPES Services", Internet-Draft: http://
www.ietf.org/internet- drafts/
draft-ietf-opes-authorization-00.txt , October 2002.
Barbir, et al. Expires August 11, 2003 [Page 15]
Internet-Draft Security Threats and Risks for OPES February 2003
Informative References
[4] Floyd, S. and L. Daigle, "IAB Architectural and Policy
Considerations for Open Pluggable Edge Services", RFC 3238,
January 2002.
Authors' Addresses
Abbie Barbir
Nortel Networks
3500 Carling Avenue
Nepean, Ontario K2H 8E9
Canada
Phone: +1 613 763 5229
EMail: abbieb@nortelnetworks.com
Oskar Batuner
Independent consultant
EMail: batuner@attbi.com
Bindignavile Srinivas
Nokia
5 Wayside Road
Burlington, MA 01803
USA
EMail: bindignavile.srinivas@nokia.com
Markus Hofmann
Bell Labs/Lucent Technologies
Room 4F-513
101 Crawfords Corner Road
Holmdel, NJ 07733
US
Phone: +1 732 332 5983
EMail: hofmann@bell-labs.com
Barbir, et al. Expires August 11, 2003 [Page 16]
Internet-Draft Security Threats and Risks for OPES February 2003
Hilarie Orman
Purple Streak Development
Phone:
EMail: ho@alum.mit.edu
Barbir, et al. Expires August 11, 2003 [Page 17]
Internet-Draft Security Threats and Risks for OPES February 2003
Appendix A. Acknowledgements
Many thanks to T. Chan (Nokia) and A. Beck (Lucent)
Barbir, et al. Expires August 11, 2003 [Page 18]
Internet-Draft Security Threats and Risks for OPES February 2003
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
Barbir, et al. Expires August 11, 2003 [Page 19]
Internet-Draft Security Threats and Risks for OPES February 2003
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Barbir, et al. Expires August 11, 2003 [Page 20]
