One document matched: draft-ietf-rserpool-threats-02.txt

Differences from draft-ietf-rserpool-threats-01.txt

Internet Engineering Task Force                 Maureen Stillman(editor)
INTERNET DRAFT                                        Ram Gopal
                                                      Senthil Sengodan
                                                      Nokia
                                                      Erik Guttman
                                                      Sun Microsystems
                                                      Matt Holdrege
                                                      Sonus Networks
                                                      15 September 2003
expires March 15, 2004

      Threats Introduced by Rserpool and Requirements for Security
                          in response to Threats
                 <draft-ietf-rserpool-threats-02.txt>



Status of This Memo


   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026 [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.


Abstract

   Rserpool is an architecture and protocols for the management and
   access to server pools supporting highly reliable applications
   and for client access mechanisms to a server pool. This Internet
   draft describes security threats to the Rserpool architecture and
   presents requirements for security to thwart these threats.













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                                Contents


Status of This Memo                                                    1
Abstract                                                               1
1. Introduction                                                        3
     1.1 Definitions  . . . . . . . . . . . . . . . . . . . . . . .    3
2. Threats                                                             4
     2.1  PE Registration/Deregistration flooding . . . . . . . . .    4
     2.2  PE Registration/Deregistration flooding . . . . . . . . .    4
     2.3  PE Registration/Deregistration spoofing . . . . . . . . .    4
     2.4  PE Registration/Deregistration unauthorized . . . . . . .    5
     2.5  Malicious ENRP server joins the group of legitimate ENRP
                          servers . . . . . . . . . . . . . . . . .    5
     2.6  Registration/deregistration with malicious ENRP servers .    5
     2.7  Malicious ENRP Name Resolution .. . . . . . . . . . . . .    5
     2.8  Malicious node performs a replay attack.. . . . . . . . .    6
     2.9  Re-establishing PU-PE security during failover. . . . . .    6
     2.10 Integrity . . . . . . . . . . . . . . . . . . . . . . . .    6
     2.11 Data Confidentiality  . . . . . . . . . . . . . . . . . .    6
     2.12 ENRP Server Discovery . . . . . . . . . . . . . . . . . .    7
     2.13 Flood of endpoint unreachable messages  . . . . . . . . .    7
     2.14 Flood of endpoint keep alive messages . . . . . . . . . .    7
3.  Security Considerations . . . . . . . . . . . . . . . . . . . .    8
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . .    8
5.  References  . . . . . . . . . . . . . . . . . . . . . . . . . .    8
6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  8
7.  Intellectual Property Statement . . . . . . . . . . . . . . . .    9
8.  Author's addresses  . . . . . . . . . . . . . . . . . . . . . . . 10
























Stillman, et al.                                               [Page 2]

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1. Introduction

RSERPOOL provides a session layer for robustness and performance.  The
session layer function may redirect communication transparently to
upper layers.  This alters the direct one-to-one association between
communicating endpoints which typically exists between clients and
services.   In particular, secure operation of protocols often relies
on assumptions at different layers regarding the identity of the
communicating party and the continuity of the communication between
endpoints.  Further, the operation of RSERPOOL itself has security
implications and risks.  The session layer is organized and operates
dynamically which imposes additional concerns for the overall security
of the end-to-end application.  This document explores the security
implications of RSERPOOL, both due to its own functions and due to its
being interposed between applications and transport interfaces.

1.1 Definitions

This document uses the following terms:

     ENRP Endpoint Name Resolution Protocol:
          Within the operational scope of Rserpool, ENRP defines the
          procedures and message formats of a distributed fault-tolerant
          registry service for storing, bookkeeping, retrieving, and
          distributing pool operation and membership information.

     ASAP Aggregate Server Access Protocol:
          A session layer protocol which uses the Endpoint Name
          Resolution Protocol (ENRP) to provide a high
          availability name space.  ASAP is responsible for the
          abstraction of the underlying transport technologies, load
          distribution management,fault management, as well as the
          presentation to the upper layer (i.e., the ASAP user) a
          unified primitive interface.

     Operation scope:
          The part of the network visible to pool users by a specific
          instance of the reliable server pooling protocols.

     Pool (or server pool):
          A collection of servers providing the same application
          functionality.

     Pool handle (or pool name):
          A logical pointer to a pool. Each server pool will be
          identifiable in the operation scope of the system by a unique
          pool handle or "name".

     ENRP namespace (or namespace):
          A cohesive structure of pool names and relations that may be
          queried by an internal or external agent.





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     Pool element (PE):
          A server entity that runs ASAP and has registered to a pool.

     Pool user (PU):
          A server pool user that runs ASAP. Note, a PU can also be a
          PE if it has registered itself to a pool.

     ENRP namespace server (or ENRP server):
          Entity which runs ENRP and is responsible for managing and
          maintaining the namespace within the operation scope.

2. Threats

2.1  PE Registration/Deregistration flooding

Threat:  A malicious node could send a stream of false
registrations/deregistrations on behalf of non-existent PEs to ENRP
servers at a very rapid rate and thereby create unnecessary state in an
ENRP server.

Effect: Corrupting the name server database and/or disabling the
Rserpool discovery and naming function.

Requirement:  An ENRP server that receives a registration/deregistration
should not create or update state information until it has authenticated
the PE.

2.2 PE Registration/Deregistration flooding

Threat: A malicious node or PE could send a stream of
registrations/deregistrations that are unauthorized to
register/deregister - to ENRP servers at a very rapid rate and thereby
create unnecessary state in an ENRP server.

Effect: Corrupting the name server database and/or disabling the
Rserpool discovery and naming function.

Requirement:  An ENRP server that receives a registration/deregistration
should not create or update state information until the authorization of
the registering/de-registering entity is verified.


2.3  PE Registration/Deregistration spoofing

Threat:  A malicious node could send false registrations/deregistrations
to ENRP servers concerning a legitimate PE thereby creating false state
information in the ENRP servers.

Effect: Misinformation in the ENRP server concerning a PE would get
propagated to other ENRP servers thereby corrupting the ENRP database.

Requirement:  An ENRP server that receives a registration/deregistration
should not create or update state information until it has authenticated
the PE.


Stillman, et al.                                                [Page 4]

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2.4  PE Registration/Deregistration unauthorized

Threat:  A PE who is not authorized to join a pool could send
registrations/deregistrations to ENRP servers thereby creating false
state information in the ENRP servers.

Effect: Misinformation in the ENRP server concerning a PE would get
propagated to other ENRP servers thereby corrupting the ENRP database.

Requirement:  An ENRP server that receives a registration/deregistration
should not create or update state information until it has authorized
the requesting entity.

2.5 Malicious ENRP server joins the group of legitimate ENRP servers

Threat: Malicious ENRP server joins the group of legitimate ENRP servers
with the intent of propagating inaccurate updates to corrupt the ENRP
database.

Effect: Inconsistent ENRP database state.

Requirement: Mutual authentication of ENRP servers.

2.6 Registration/deregistration with malicious ENRP server

Threat: A PE unknowingly registers/deregisters with malicious ENRP
server.

Effect: Registration might not be properly processed or ignored.

Requirement: PE needs to authenticate the ENRP server.


2.7 Malicious ENRP Name Resolution

Threat: The ASAP protocol receives a name resolution response from an
ENRP server, but the ENRP server is malicious and returns random IP
addresses or an inaccurate list in response to the pool handle.

Effect: PU application communicates with the wrong PE or is unable to
locate the PE since the response is incorrect in saying that a PE with
that name did not exist.

Requirement: ASAP needs to authenticate the ENRP server.











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2.8 Malicious node performs a replay attack

Threat: A malicious node could replay the entire message previously sent
by a legitimate entity. This could create false/unnecessary state in the
ENRP servers when the replay is for registration/de-registration or
update.

Effect: False/extra state is maintained by ENRP servers

Requirement:  Care should be taken to prevent replay attacks.

2.9 Re-establishing PU-PE security during failover

Threat: PU fails over from PE A to PE B.  In the case that the PU had a
trusted relationship with PE A, then the PU will likely not have the
same relationship established with PE B.

Effect: If there was a trust relationship involving security context
between PU and PE A, the equivalent trust relationship will not exist
between PU and PE B.  This will violate security policy.

Requirement: Either notify the application when fail over occurs so the
application can take appropriate action to establish a trusted
relationship with PE B OR reestablish the security context
transparently.

2.10  Integrity

Threats:
a) ENRP response to name resolution is corrupted during transmission
b) ENRP peer messages are corrupted during transmission
c) PE sends update for values and that information is corrupted during
transmission

Effect: ASAP receives corrupt information for pool handle resolution
which the PU believes to be accurate.

Requirement: Integrity mechanism needed.

2.11 Data Confidentiality

Threat: An eavesdropper capable of snooping on fields within messages in
transit, may be able to garner information such as topology/location/IP
addresses etc. that may not be desirable to divulge.

Effect: Information that an administrator does not wish to divulge are
divulged.

Requirement: Provision for Data confidentiality service.






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2.12 ENRP Server Discovery

Threat A thwarting successful discovery: When a PE wishes to register
with an ENRP server, it needs to discover an ENRP server. An attacker
could thwart the successful discovery of ENRP server(s) thereby inducing
the PE to believe that no ENRP server is available. For instance, the
attacker could reduce the returned set of ENRP servers to null or a
small set of inactive ENRP servers.

Threat B: A similar thwarting scenario also applies when an ENRP server
or ASAP on behalf of a PU needs to discover ENRP servers.

Threat C: Spoofing successful discovery:  An attacker could spoof the
discovery by claiming to be a legitimate ENRP server.  When a PE wishes
to register, it finds the spoofed ENRP server.

Threat D: A similar spoofing scenario also applies when an ENRP server
or ASAP on behalf of a PU needs to discover ENRP servers.

Effect A: A PE that could have been in an application server pool does
not become part of a pool. The PE does not complete discovery operation.
This is a DOS attack.

Effect B: An ENRP server that could have been in an ENRP server pool
does not become part of a pool.  A PU is unable to utilize services of
ENRP servers.

Effect C,D: This malicious ENRP would either misrepresent, ignore
or otherwise hide or distort information about the PE to subvert
RSERPOOL operation.

Requirement: Discovery phase needs to be authenticated.

2.13 Flood of endpoint unreachable messages from the PU to the ENRP
server

These messages are sent by ASAP to the ENRP server when it is unable to
contact a PE.  There is the potential that a PU could flood the ENRP
server intentionally or unintentionally with these messages.

Effect: DOS attack on the ENRP server

Requirement: Need to limit the number of endpoint unreachable messages
sent to the ENRP server from the PU.

2.14 Flood of endpoint keep alive messages from the ENRP server to a PE

These messages would be sent in response to a flood of endpoint
unreachable messages from the PUs to the ENRP server.

Effect: Unintentional DOS attack on the PE

Requirement: ENRP must limit the frequency of keep alive messages to a
given PE to prevent overwhelming the PE.


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3. Security Considerations for Rserpool

This informational document characterizes potential security threats
targeting the Rserpool architecture.

4. IANA Considerations

This document introduces no additional considerations for IANA.

5. References

Normative References:

[Rserarch] M. Tuexen, et. al., "Architecture for Reliable Server
Pooling", draft-ietf-reserpool-arch-06.txt, June, 2003, work in
progress.

Informative References:

[RFC2026] S. Bradner, "The Internet Standards Process -- Revision 3",
RFC 2026, October 1996.

[RFC3365] RFC 3365, Strong Security Requirements for IETF Standard
Protocols, August, 2002.

6. Acknowledgements

Thanks to the Rserpool security design team and others that provided
valuable comments: Lyndon Ong, Randy Stewart, Melinda Shore, Qiaobing
Xie, Michael Tuexen, Aron Silverton, Sohrab Modi, Javier Pastor-Balbas,
Xingang Guo, M. Piramanayagam, Bernard Aboba and Dhooria Manoj.

Funding for the RFC Editor function is currently provided by the
Internet Society.





















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7. 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
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   proprietary rights by implementors or users of this specification can
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   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
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   The limited permissions granted above are perpetual and will not be
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   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.






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expires 15 March 2004

8. Author's Addresses

Ram Gopal
Nokia Research Center
5 Wayside Road
Burlington, MA 01803
USA
email: ram.gopal@nokia.com

Erik Guttman
Sun Microsystems
Eichhoelzelstr. 7
74915 Waibstadt
Germany
Email: Erik.Guttman@sun.com

Matt Holdrege
Sonus Networks
223 Ximeno Avenue
Long Beach, CA 90803
matt@sonusnet.com

Senthil Sengodan
Nokia Research Center
5 Wayside Road
Burlington, MA 01803
USA
email: Senthil.sengodan@nokia.com

Maureen Stillman
Nokia
35 Woodcrest Ave.
Ithaca, NY 14850
USA
email: maureen.stillman@nokia.com




















Stillman, et al.                                               [Page 10]