draft-ietf-rserpool-threats-15.txt   rfc5355.txt 
Network Working Group M. Stillman, Ed. Network Working Group M. Stillman, Ed.
Internet-Draft Nokia Request for Comments: 5355 Nokia
Intended status: Informational R. Gopal Category: Informational R. Gopal
Expires: January 9, 2009 Nokia Siemens Networks Nokia Siemens Networks
E. Guttman E. Guttman
Sun Microsystems Sun Microsystems
M. Holdrege
Strix Systems
S. Sengodan S. Sengodan
Nokia Siemans Networks Nokia Siemens Networks
July 8, 2008 M. Holdrege
September 2008
Threats Introduced by RSerPool and Requirements for Security in Response
to Threats
draft-ietf-rserpool-threats-15.txt
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Abstract Abstract
RSerPool is an architecture and set of protocols for the management Reliable Server Pooling (RSerPool) is an architecture and set of
and access to server pools supporting highly reliable applications protocols for the management and access to server pools supporting
and for client access mechanisms to a server pool. This Internet highly reliable applications and for client access mechanisms to a
draft describes security threats to the RSerPool architecture and server pool. This document describes security threats to the
presents requirements for security to thwart these threats. RSerPool architecture and presents requirements for security to
thwart these threats.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................3
1.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Definitions ................................................3
1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Conventions ................................................4
2. Threats . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Threats .........................................................4
2.1. PE Registration/Deregistration flooding -- 2.1. PE Registration/De-Registration Flooding --
non-existent PE . . . . . . . . . . . . . . . . . . . . . 4 Non-Existent PE ............................................4
2.2. PE Registration/Deregistration flooding -- 2.2. PE Registration/De-Registration Flooding --
unauthorized PE . . . . . . . . . . . . . . . . . . . . . 5 Unauthorized PE ............................................5
2.3. PE Registration/Deregistration spoofing . . . . . . . . . 6 2.3. PE Registration/De-Registration Spoofing ...................6
2.4. PE Registration/Deregistration unauthorized . . . . . . . 6 2.4. PE Registration/De-Registration Unauthorized ...............6
2.5. Malicious ENRP server joins the group of legitimate 2.5. Malicious ENRP Server Joins the Group of Legitimate
ENRP servers . . . . . . . . . . . . . . . . . . . . . . . 7 ENRP Servers ...............................................7
2.6. Registration/deregistration with malicious ENRP server . . 7 2.6. Registration/De-Registration with Malicious ENRP Server ....7
2.7. Malicious ENRP Handlespace Resolution . . . . . . . . . . 8 2.7. Malicious ENRP Handlespace Resolution ......................8
2.8. Malicious node performs a replay attack . . . . . . . . . 9 2.8. Malicious Node Performs a Replay Attack ....................9
2.9. Re-establishing PU-PE security during failover . . . . . . 9 2.9. Re-Establishing PU-PE Security during Failover .............9
2.10. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 9 2.10. Integrity ................................................10
2.11. Data Confidentiality . . . . . . . . . . . . . . . . . . . 10 2.11. Data Confidentiality .....................................10
2.12. ENRP Server Discovery . . . . . . . . . . . . . . . . . . 11 2.12. ENRP Server Discovery ....................................11
2.13. Flood of endpoint unreachable messages from the PU to 2.13. Flood of Endpoint-Unreachable Messages from the
the ENRP server . . . . . . . . . . . . . . . . . . . . . 12 PU to the ENRP Server ....................................12
2.14. Flood of endpoint keep alive messages from the ENRP 2.14. Flood of Endpoint Keep-Alive Messages from the
server to a PE . . . . . . . . . . . . . . . . . . . . . . 12 ENRP Server to a PE ......................................12
2.15. Security of the ENRP database . . . . . . . . . . . . . . 13 2.15. Security of the ENRP Database ............................13
2.16. Cookie mechanism security . . . . . . . . . . . . . . . . 13 2.16. Cookie Mechanism Security ................................13
2.17. Potential insider attacks from legitmate ENRP servers . . 14 2.17. Potential Insider Attacks from Legitimate ENRP Servers ...14
3. Security Considerations . . . . . . . . . . . . . . . . . . . 15 3. Security Considerations ........................................15
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 4. Normative References ...........................................17
5. Normative References . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . . . 19
1. Introduction 1. Introduction
The RSerPool architecture[I-D.ietf-rserpool-overview] supports high- The RSerPool architecture [RFC5351] supports high-availability and
availability and load balancing by enabling a pool user to identify load balancing by enabling a pool user to identify the most
the most appropriate server from the server pool at a given time. appropriate server from the server pool at a given time. The
The architecture is defined to support a set of basic goals. These architecture is defined to support a set of basic goals. These
include an application-independent protocol mechanisms, separation of include application-independent protocol mechanisms, separation of
server naming from IP addressing, the use of the end-to-end principle server naming from IP addressing, the use of the end-to-end principle
to avoid dependencies on intermediate equipment, separation of to avoid dependencies on intermediate equipment, separation of
session availability/failover functionality from application itself, session availability/failover functionality from the application
the ability to facilitate different server selection policies, the itself, the ability to facilitate different server selection
ability to facilitate a set of application-independent failover policies, the ability to facilitate a set of application-independent
capabilities and a peer-to-peer structure. failover capabilities, and a peer-to-peer structure.
RSerPool provides a session layer for robustness. The session layer RSerPool provides a session layer for robustness. The session layer
function may redirect communication transparently to upper layers. function may redirect communication transparently to upper layers.
This alters the direct one-to-one association between communicating This alters the direct one-to-one association between communicating
endpoints which typically exists between clients and servers. In endpoints that typically exists between clients and servers. In
particular, secure operation of protocols often relies on assumptions particular, secure operation of protocols often relies on assumptions
at different layers regarding the identity of the communicating party at different layers regarding the identity of the communicating party
and the continuity of the communication between endpoints. Further, and the continuity of the communication between endpoints. Further,
the operation of RSerPool itself has security implications and risks. the operation of RSerPool itself has security implications and risks.
The session layer operates dynamically which imposes additional The session layer operates dynamically, which imposes additional
concerns for the overall security of the end-to-end application. concerns for the overall security of the end-to-end application.
This document explores the security implications of RSerPool, both This document explores the security implications of RSerPool, both
due to its own functions and due to its being interposed between due to its own functions and due to its being interposed between
applications and transport interfaces. applications and transport interfaces.
This document is related to the RSerPool This document is related to the RSerPool Aggregate Server Access
ASAP[I-D.ietf-rserpool-asap]and ENRP [I-D.ietf-rserpool-enrp]protocol Protocol (ASAP) [RFC5352] and Endpoint Name Resolution Protocol
documents which describe in their security consideration sections the (ENRP) [RFC5353] documents, which describe, in their Security
mechanisms for meeting the security requirements in this document. Consideration sections, the mechanisms for meeting the security
TLS[RFC4346] is the security mechanism for RSerPool that was selected requirements in this document. TLS [RFC5246] is the security
to meet all the requirements described in this document. The mechanism for RSerPool that was selected to meet all the requirements
security considerations section of ASAP and ENRP describes how TLS is described in this document. The Security Considerations sections of
actually used to provide the security that is discussed in this ASAP and ENRP describe how TLS is actually used to provide the
document. security that is discussed in this document.
1.1. Definitions 1.1. Definitions
This document uses the following terms: This document uses the following terms:
Endpoint Name Resolution Protocol (ENRP): Endpoint Name Resolution Protocol (ENRP):
Within the operational scope of RSerPool, Within the operational scope of RSerPool, ENRP[RFC5353] defines
ENRP[I-D.ietf-rserpool-enrp] defines the procedures and message the procedures and message formats of a distributed fault-tolerant
formats of a distributed fault-tolerant registry service for registry service for storing, bookkeeping, retrieving, and
storing, bookkeeping, retrieving, and distributing pool operation distributing pool operation and membership information.
and membership information.
Aggregate Server Access Protocol (ASAP): Aggregate Server Access Protocol (ASAP):
ASAP[I-D.ietf-rserpool-asap] is a session layer protocol which ASAP [RFC5352] is a session layer protocol that uses ENRP to
uses ENRP to provide a high availability handlespace. ASAP is provide a high-availability handlespace. ASAP is responsible for
responsible for the abstraction of the underlying transport the abstraction of the underlying transport technologies, load
technologies, load distribution management,fault management, as distribution management, fault management, as well as the
well as the presentation to the upper layer (i.e., the ASAP user) presentation to the upper layer (i.e., the ASAP User) of a unified
a unified primitive interface. primitive interface.
Operational scope: Operational scope:
The part of the network visible to pool users by a specific The part of the network visible to pool users by a specific
instance of the reliable server pooling protocols. instance of the Reliable Server Pooling protocols.
Pool (or server pool): Pool (or server pool):
A collection of servers providing the same application A collection of servers providing the same application
functionality. functionality.
Pool handle: Pool handle:
A logical pointer to a pool. Each server pool will be A logical pointer to a pool. Each server pool will be
identifiable in the operational scope of the system by a unique identifiable in the operational scope of the system by a unique
pool handle. pool handle.
skipping to change at page 4, line 45 skipping to change at page 4, line 44
Pool user (PU): A server pool user. Pool user (PU): A server pool user.
1.2. Conventions 1.2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Threats 2. Threats
2.1. PE Registration/Deregistration flooding -- non-existent PE 2.1. PE Registration/De-Registration Flooding -- Non-Existent PE
2.1.1. Threat 2.1.1. Threat
A malicious node could send a stream of false registrations/ A malicious node could send a stream of false registrations/de-
deregistrations on behalf of non-existent PEs to ENRP servers at a registrations on behalf of non-existent PEs to ENRP servers at a very
very rapid rate and thereby create unnecessary state in an ENRP rapid rate and thereby create unnecessary state in an ENRP server.
server.
2.1.2. Effect 2.1.2. Effect
The malicious node will corrupt the pool registrar database and/or The malicious node will corrupt the pool registrar database and/or
disable the RSerPool discovery and database function. This disable the RSerPool discovery and database function. This
represents a denial of service attack as the PU would potentially get represents a denial-of-service attack, as the PU would potentially
an IP address of a non-existent PE in response to an ENRP query. get an IP address of a non-existent PE in response to an ENRP query.
2.1.3. Requirement 2.1.3. Requirement
An ENRP server that receives a registration/deregistration MUST NOT An ENRP server that receives a registration/de-registration MUST NOT
create or update state information until it has authenticated the PE. create or update state information until it has authenticated the PE.
TLS with PSK is mandatory to implement as the authentication TLS with a pre-shared-key (PSK) is mandatory to implement as the
mechanism. For PSK, having a pre-shared-key constitutes authentication mechanism. For PSK, having a pre-shared-key
authorization.The network administrators of a pool need to decide constitutes authorization. The network administrators of a pool need
which nodes are authorized to participate in the pool. The to decide which nodes are authorized to participate in the pool. The
justification for PSK is that we assume that one administrative justification for PSK is that we assume that one administrative
domain will control and manage the server pool. This allows for PSK domain will control and manage the server pool. This allows for PSK
to be implemented and managed by a central security administrator. to be implemented and managed by a central security administrator.
2.2. PE Registration/Deregistration flooding -- unauthorized PE 2.2. PE Registration/De-Registration Flooding -- Unauthorized PE
2.2.1. Threat 2.2.1. Threat
A malicious node or PE could send a stream of registrations/ A malicious node or PE could send a stream of registrations/de-
deregistrations that are unauthorized to register/deregister - to registrations that are unauthorized to register/de-register to ENRP
ENRP servers at a very rapid rate and thereby create unnecessary servers at a very rapid rate and thereby create unnecessary state in
state in an ENRP server. an ENRP server.
2.2.2. Effect 2.2.2. Effect
This attack will corrupt the pool registrar database and/or disable This attack will corrupt the pool registrar database and/or disable
the RSerPool discovery and database function. There is the potential the RSerPool discovery and database function. There is the potential
for two types of attacks, denial of service and data interception. for two types of attacks: denial of service and data interception.
In the denial of service attack, the PU gets an IP address of a rogue In the denial-of-service attack, the PU gets an IP address of a rogue
PE in response to an ENRP query which might not provide the actual PE in response to an ENRP query, which might not provide the actual
service. In addition, a flood of message could prevent legitimate service. In addition, a flood of message could prevent legitimate
PEs from registering. In the data interception attack, the rogue PE PEs from registering. In the data interception attack, the rogue PE
does provide the service as man in the middle which allows the does provide the service as a man in the middle (MITM), which allows
attacker to collect data. the attacker to collect data.
2.2.3. Requirement 2.2.3. Requirement
An ENRP server that receives a registration/deregistration MUST NOT An ENRP server that receives a registration/de-registration MUST NOT
create or update state information until the authentication create or update state information until the authentication
information of the registering/de-registering entity is verified. information of the registering/de-registering entity is verified.
TLS is used as the authentication mechanism between the ENRP server TLS is used as the authentication mechanism between the ENRP server
and PE. TLS with PSK is mandatory to implement as the authentication and PE. TLS with PSK is mandatory to implement as the authentication
mechanism. For PSK, having a pre-shared-key constitutes mechanism. For PSK, having a pre-shared-key constitutes
authorization.The network administrators of a pool need to decide authorization.The network administrators of a pool need to decide
which nodes are authorized to participate in the pool. which nodes are authorized to participate in the pool.
2.3. PE Registration/Deregistration spoofing 2.3. PE Registration/De-Registration Spoofing
2.3.1. Threat 2.3.1. Threat
A malicious node could send false registrations/deregistrations to A malicious node could send false registrations/de-registrations to
ENRP servers concerning a legitimate PE thereby creating false state ENRP servers concerning a legitimate PE, thereby creating false state
information in the ENRP servers. information in the ENRP servers.
2.3.2. Effect 2.3.2. Effect
This would generate misinformation in the ENRP server concerning a PE This would generate misinformation in the ENRP server concerning a PE
and would be propagated to other ENRP servers thereby corrupting the and would be propagated to other ENRP servers, thereby corrupting the
ENRP database. DDoS, by adding a PE that is a target for DDoS attack ENRP database. Distributed Denial of Service (DDoS) could result: if
for some popular high volume service the attacker can register a PE a PE that is a target for a DDoS attack for some popular high-volume
that a lot of PUs will try to connect to. This allows man in the service, then the attacker can register a PE to which a lot of PUs
middle or masquerade attacks on the service provided by the will try to connect. This allows man-in-the-middle or masquerade
legitimate PEs. If a attacker registers its server address as a PE attacks on the service provided by the legitimate PEs. If an
and handles the requests he can eavesdrop on service data. attacker registers its server address as a PE and handles the
requests, he can eavesdrop on service data.
2.3.3. Requirement 2.3.3. Requirement
An ENRP server that receives a registration/deregistration MUST NOT An ENRP server that receives a registration/de-registration MUST NOT
create or update state information until it has authenticated the PE. create or update state information until it has authenticated the PE.
TLS is used as the authentication mechanism between the ENRP server TLS is used as the authentication mechanism between the ENRP server
and the PE. TLS with PSK is mandatory to implement as the and the PE. TLS with PSK is mandatory to implement as the
authentication mechanism. For PSK, having a pre-shared-key authentication mechanism. For PSK, having a pre-shared-key
constitutes authorization.The network administrators of a pool need constitutes authorization.The network administrators of a pool need
to decide which nodes are authorized to participate in the pool. A to decide which nodes are authorized to participate in the pool. A
PE can register only for itself and cannot register on behalf of PE can register only for itself and cannot register on behalf of
other PEs. other PEs.
2.4. PE Registration/Deregistration unauthorized 2.4. PE Registration/De-Registration Unauthorized
2.4.1. Threat 2.4.1. Threat
A PE who is not authorized to join a pool could send registrations/ A PE that is not authorized to join a pool could send registrations/
deregistrations to ENRP servers thereby creating false state de-registrations to ENRP servers, thereby creating false state
information in the ENRP servers. information in the ENRP servers.
2.4.2. Effect 2.4.2. Effect
This attack would generate misinformation in the ENRP server This attack would generate misinformation in the ENRP server
concerning a PE and would be propagated to other ENRP servers thereby concerning a PE and would be propagated to other ENRP servers thereby
corrupting the ENRP database. This allows man in the middle or corrupting the ENRP database. This allows man-in-the-middle or
masquerade attacks on the service provided by the legitimate PEs. If masquerade attacks on the service provided by the legitimate PEs. If
a attacker registers its server address as a PE and handles the an attacker registers its server address as a PE and handles the
requests he can eavesdrop on service data. requests, he can eavesdrop on service data.
2.4.3. Requirement 2.4.3. Requirement
An ENRP server that receives a registration/deregistration MUST NOT An ENRP server that receives a registration/de-registration MUST NOT
create or update state information until it has authorized the create or update state information until it has authorized the
requesting entity. TLS is used as the authentication mechanism. TLS requesting entity. TLS is used as the authentication mechanism. TLS
with PSK is mandatory to implement as the authentication mechanism. with PSK is mandatory to implement as the authentication mechanism.
For PSK, having a pre-shared-key constitutes authorization.The For PSK, having a pre-shared-key constitutes authorization.The
network administrators of a pool need to decide which nodes are network administrators of a pool need to decide which nodes are
authorized to participate in the pool. authorized to participate in the pool.
2.5. Malicious ENRP server joins the group of legitimate ENRP servers 2.5. Malicious ENRP Server Joins the Group of Legitimate ENRP Servers
2.5.1. Threat 2.5.1. Threat
A malicious ENRP server joins the group of legitimate ENRP servers A malicious ENRP server joins the group of legitimate ENRP servers
with the intent of propagating inaccurate updates to corrupt the ENRP with the intent of propagating inaccurate updates to corrupt the ENRP
database. The attacker sets up an ENRP server and attempts to database. The attacker sets up an ENRP server and attempts to
communicate with other ENRP servers. communicate with other ENRP servers.
2.5.2. Effect 2.5.2. Effect
The result would be Inconsistent ENRP database state. The result would be Inconsistent ENRP database state.
2.5.3. Requirement 2.5.3. Requirement
ENRP servers MUST perform mutual authentication. This would prevent ENRP servers MUST perform mutual authentication. This would prevent
the attacker from joining its ENRP server to the pool. TLS is used the attacker from joining its ENRP server to the pool. TLS is used
as the mutual authentication mechanism. TLS with PSK is mandatory to as the mutual authentication mechanism. TLS with PSK is mandatory to
implement as the authentication mechanism. For PSK, having a pre- implement as the authentication mechanism. For PSK, having a
shared-key constitutes authorization.The network administrators of a pre-shared-key constitutes authorization. The network administrators
pool need to decide which nodes are authorized to participate in the of a pool need to decide which nodes are authorized to participate in
pool. the pool.
2.6. Registration/deregistration with malicious ENRP server 2.6. Registration/De-Registration with Malicious ENRP Server
2.6.1. Threat 2.6.1. Threat
A PE unknowingly registers/deregisters with malicious ENRP server. A PE unknowingly registers/de-registers with a malicious ENRP server.
2.6.2. Effect 2.6.2. Effect
The registration might not be properly processed or ignored. A rogue The registration might not be properly processed or it might be
ENRP server has the ability to return any address to a user ignored. A rogue ENRP server has the ability to return any address
requesting service which could result in denial of service or to a user requesting service; this ability could result in denial of
connection to a rouge PE of the attackers choice for service. service or connection to a rogue PE that is the attacker's choice for
service.
2.6.3. Requirement 2.6.3. Requirement
The PE MUST authenticate the ENRP server. TLS is the mechanism used The PE MUST authenticate the ENRP server. TLS is the mechanism used
for the authentication. TLS with PSK is mandatory to implement as for the authentication. TLS with PSK is mandatory to implement as
the authentication mechanism. For PSK, having a pre-shared-key the authentication mechanism. For PSK, having a pre-shared-key
constitutes authorization.The network administrators of a pool need constitutes authorization.The network administrators of a pool need
to decide which nodes are authorized to participate in the pool. to decide which nodes are authorized to participate in the pool.
This requirement prevents malicious outsiders and insiders from This requirement prevents malicious outsiders and insiders from
adding their own ENRP server to the pool. adding their own ENRP server to the pool.
skipping to change at page 8, line 32 skipping to change at page 8, line 33
2.7. Malicious ENRP Handlespace Resolution 2.7. Malicious ENRP Handlespace Resolution
2.7.1. Threat 2.7.1. Threat
The ASAP protocol receives a handlespace resolution response from an The ASAP protocol receives a handlespace resolution response from an
ENRP server, but the ENRP server is malicious and returns random IP ENRP server, but the ENRP server is malicious and returns random IP
addresses or an inaccurate list in response to the pool handle. addresses or an inaccurate list in response to the pool handle.
2.7.2. Effect 2.7.2. Effect
PU application communicates with the wrong PE or is unable to locate The PU application communicates with the wrong PE or is unable to
the PE since the response is incorrect in saying that a PE with that locate the PE since the response is incorrect in saying that a PE
handle did not exist. A rouge ENRP server has the ability to return with that handle did not exist. A rogue ENRP server has the ability
any address to ASAP requesting an address list which could result in to return any address to ASAP requesting an address list that could
denial of service or connection to a rouge PE of the attackers choice result in denial of service or connection to a rogue PE of the
for service. From the PE, the attacker could eavesdrop or tamper attacker's choice for service. From the PE, the attacker could
with the application. eavesdrop or tamper with the application.
2.7.3. Requirement 2.7.3. Requirement
ASAP SHOULD authenticate the ENRP server. TLS with certificates is ASAP SHOULD authenticate the ENRP server. TLS with certificates is
the mandatory to implement mechanism used for authentication. The the mandatory-to-implement mechanism used for authentication. The
administrator uses a centralized CA to generate and sign administrator uses a centralized Certificate Authority (CA) to
certificates. The certificate is stored on the ENRP server. A CA generate and sign certificates. The certificate is stored on the
trusted root certification authority certificate is sent to the ENRP server. A CA trusted root certification authority certificate
client out of band and the certificate signature on the ENRP server is sent to the client out of band, and the certificate signature on
certificate is checked for validity during TLS handshake. This the ENRP server certificate is checked for validity during the TLS
authentication prevents malicious outsiders and insiders from adding handshake. This authentication prevents malicious outsiders and
an ENRP server to the pool that may be accessed by ASAP. insiders from adding an ENRP server to the pool that may be accessed
by ASAP.
2.8. Malicious node performs a replay attack 2.8. Malicious Node Performs a Replay Attack
2.8.1. Threat 2.8.1. Threat
A malicious node could replay the entire message previously sent by a A malicious node could replay the entire message previously sent by a
legitimate entity. This could create false/unnecessary state in the legitimate entity. This could create false/unnecessary state in the
ENRP servers when the replay is for registration/de-registration or ENRP servers when the replay is for registration/de-registration or
update. update.
2.8.2. Effect 2.8.2. Effect
The result is that false/extra state is maintained by ENRP servers. The result is that false/extra state is maintained by ENRP servers.
This would most likely be used as a denial of service attack if the This would most likely be used as a denial-of-service attack if the
replay is used to deregister all PEs. replay is used to de-register all PEs.
2.8.3. Requirement 2.8.3. Requirement
The protocol MUST prevent replay attacks. The replay attack The protocol MUST prevent replay attacks. The replay attack
prevention mechanism in TLS meets this requirement. prevention mechanism in TLS meets this requirement.
2.9. Re-establishing PU-PE security during failover 2.9. Re-Establishing PU-PE Security during Failover
2.9.1. Threat 2.9.1. Threat
PU fails over from PE A to PE B. In the case that the PU had a The 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 trusted relationship with PE A, the PU will likely not have the same
same relationship established with PE B. relationship established with PE B.
2.9.2. Effect 2.9.2. Effect
If there was a trust relationship involving security context between 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 A, the equivalent trust relationship will not exist between
PU and PE B. This will violate security policy. For example, if the PU and PE B. This will violate security policy. For example, if the
security context with A involves encryption and the security context security context with A involves encryption and the security context
with B does not then an attacker could take advantage of the change with B does not, then an attacker could take advantage of the change
in security. in security.
2.9.3. Requirement 2.9.3. Requirement
The application SHOULD be notified when fail over occurs so the The application SHOULD be notified when fail over occurs so the
application can take appropriate action to establish a trusted application can take appropriate action to establish a trusted
relationship with PE B. ENRP has a mechanism to perform this relationship with PE B. ENRP has a mechanism to perform this
function. function.
2.10. Integrity 2.10. Integrity
2.10.1. Threat 2.10.1. Threat
The following are all instances of the same class of threats, and all The following are all instances of the same class of threats, and all
have similar effects. have similar effects.
a. ENRP response to pool handle resolution is corrupted during a. ENRP response to pool handle resolution is corrupted during
transmission transmission.
b. ENRP peer messages are corrupted during transmission b. ENRP peer messages are corrupted during transmission.
c. PE sends update for values and that information is corrupted c. PE sends an update for values, and that information is corrupted
during transmission during transmission.
2.10.2. Effect 2.10.2. Effect
The result is that ASAP receives corrupt information for pool handle The result is that ASAP receives corrupt information for pool handle
resolution which the PU believes to be accurate. This corrupt resolution, which the PU believes to be accurate. This corrupt
information could be an IP address that does not resolve to a PE so information could be an IP address that does not resolve to a PE so
the PU would not be able to contact the server. the PU would not be able to contact the server.
2.10.3. Requirement 2.10.3. Requirement
An integrity mechanism MUST be present. Corruption of data that is An integrity mechanism MUST be present. Corruption of data that is
passed to the PU means that the PU can't rely on it. The consequence passed to the PU means that the PU can't rely on it. The consequence
of corrupted information is that the IP addresses passed to the PU of corrupted information is that the IP addresses passed to the PU
might be wrong in which case it will not be able to reach the PE. might be wrong, in which case, it will not be able to reach the PE.
The interfaces that MUST implement integrity are PE to ENRP server The interfaces that MUST implement integrity are PE to ENRP server
and ENRP to ENRP server. The integrity mechanism in TLS is used for and ENRP to ENRP server. The integrity mechanism in TLS is used for
this. this.
2.11. Data Confidentiality 2.11. Data Confidentiality
2.11.1. Threat 2.11.1. Threat
An eavesdropper capable of snooping on fields within messages in An eavesdropper capable of snooping on fields within messages in
transit, may be able to gather information such as transit may be able to gather information, such as
topology/location/IP addresses etc. that may not be desirable to topology/location/IP addresses, etc., which may not be desirable to
divulge. divulge.
2.11.2. Effect 2.11.2. Effect
Information that an administrator does not wish to divulge is Information that an administrator does not wish to divulge is
divulged. The attacker gains valuable information that can be used divulged. The attacker gains valuable information that can be used
for financial gain or attacks on hosts. for financial gain or attacks on hosts.
2.11.3. Requirement 2.11.3. Requirement
A provision for data confidentiality service SHOULD be available. A provision for data confidentiality service SHOULD be available.
TLS provides data confidentiality in support of this mechanism. TLS provides data confidentiality in support of this mechanism.
2.12. ENRP Server Discovery 2.12. ENRP Server Discovery
2.12.1. Threats 2.12.1. Threats
a. Thwarting successful discovery: When a PE wishes to register with a. Thwarting successful discovery: When a PE wishes to register with
an ENRP server, it needs to discover an ENRP server. An attacker an ENRP server, it needs to discover an ENRP server. An attacker
could thwart the successful discovery of ENRP server(s) thereby could thwart the successful discovery of ENRP server(s), thereby
inducing the PE to believe that no ENRP server is available. For inducing the PE to believe that no ENRP server is available. For
instance, the attacker could reduce the returned set of ENRP instance, the attacker could reduce the returned set of ENRP
servers to null or a small set of inactive ENRP servers. The servers to null or a small set of inactive ENRP servers. The
attacker performs a MITM attack to do this. attacker performs a MITM attack to do this.
b. A similar thwarting scenario also applies when an ENRP server or b. A similar thwarting scenario also applies when an ENRP server or
ASAP on behalf of a PU needs to discover ENRP servers. ASAP on behalf of a PU needs to discover ENRP servers.
c. Spoofing successful discovery: An attacker could spoof the c. Spoofing successful discovery: An attacker could spoof the
discovery by claiming to be a legitimate ENRP server. When a PE discovery by claiming to be a legitimate ENRP server. When a PE
wishes to register, it finds the spoofed ENRP server. An wishes to register, it finds the spoofed ENRP server. An
attacker can only make such a claim if no security mechanisms are attacker can only make such a claim if no security mechanisms are
used. used.
d. A similar spoofing scenario also applies when an ENRP server or d. A similar spoofing scenario also applies when an ENRP server or
ASAP on behalf of a PU needs to discover ENRP servers. ASAP on behalf of a PU needs to discover ENRP servers.
2.12.2. Effects (letters correlate with threats above) 2.12.2. Effects (Letters Correlate with Threats above)
a. A PE that could have been in an application server pool does not 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 become part of a pool. The PE does not complete discovery
operation. This is a DOS attack. operation. This is a DoS attack.
b. An ENRP server that could have been in an ENRP server pool does 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 not become part of a pool. A PU is unable to utilize services of
ENRP servers. ENRP servers.
c. This malicious ENRP would either misrepresent, ignore or c. This malicious ENRP would either misrepresent, ignore, or
otherwise hide or distort information about the PE to subvert otherwise hide or distort information about the PE to subvert
RSerPool operation. RSerPool operation.
d. Same as above. d. Same as above.
2.12.3. Requirement 2.12.3. Requirement
A provision for authentication MUST be present and a provision for A provision for authentication MUST be present and a provision for
data confidentiality service SHOULD be present. TLS has a mechanism data confidentiality service SHOULD be present. TLS has a mechanism
for confidentiality. for confidentiality.
2.13. Flood of endpoint unreachable messages from the PU to the ENRP 2.13. Flood of Endpoint-Unreachable Messages from the PU to the ENRP
server Server
2.13.1. Threat 2.13.1. Threat
Endpoint unreachable messages are sent by ASAP to the ENRP server Endpoint-unreachable messages are sent by ASAP to the ENRP server
when it is unable to contact a PE. There is the potential that a PU when it is unable to contact a PE. There is the potential that a PU
could flood the ENRP server intentionally or unintentionally with could flood the ENRP server intentionally or unintentionally with
these messages. The non-malicious case would require an incorrect these messages. The non-malicious case would require an incorrect
implementation. The malicious case would be caused by writing code implementation. The malicious case would be caused by writing code
to flood the ENRP server with endpoint unreachable messages. to flood the ENRP server with endpoint unreachable messages.
2.13.2. Effect 2.13.2. Effect
The result is a DOS attack on the ENRP server. The ENRP server would The result is a DoS attack on the ENRP server. The ENRP server would
not be able to service other PUs effectively and would not be able to not be able to service other PUs effectively and would not be able to
take registrations from PEs in a timely manner. Further, it would take registrations from PEs in a timely manner. Further, it would
not be able to communicate with other ENRP servers in the pool to not be able to communicate with other ENRP servers in the pool to
update the database in a timely fashion. update the database in a timely fashion.
2.13.3. Requirement 2.13.3. Requirement
The number of endpoint unreachable messages sent to the ENRP server The number of endpoint unreachable messages sent to the ENRP server
from the PU SHOULD be limited. This mechanism is described in the from the PU SHOULD be limited. This mechanism is described in the
ASAP[I-D.ietf-rserpool-asap] protocol document. ASAP [RFC5352] protocol document.
2.14. Flood of endpoint keep alive messages from the ENRP server to a 2.14. Flood of Endpoint Keep-Alive Messages from the ENRP Server to a
PE PE
2.14.1. Threat 2.14.1. Threat
Endpoint keep-alive messages would be sent from the ENRP server to Endpoint Keep-Alive messages would be sent from the ENRP server to
the PEs during the process of changing the home ENRP server for this the PEs during the process of changing the Home ENRP server for this
PE. PE.
2.14.2. Effect 2.14.2. Effect
If the ENRP server maliciously sent a flood of endpoint keep alive If the ENRP server maliciously sent a flood of endpoint Keep-Alive
messages to the PE, the PE would not be able to service clients. The messages to the PE, the PE would not be able to service clients. The
result is an unintentional DOS attack on the PE. result is a DoS attack on the PE.
2.14.3. Requirement 2.14.3. Requirement
ENRP MUST limit the frequency of keep alive messages to a given PE to ENRP MUST limit the frequency of Keep-Alive messages to a given PE to
prevent overwhelming the PE. This mechanism is described in prevent overwhelming the PE. This mechanism is described in the ENRP
ENRP.[I-D.ietf-rserpool-enrp] protocol document. [RFC5353] protocol document.
2.15. Security of the ENRP database 2.15. Security of the ENRP Database
2.15.1. Threat 2.15.1. Threat
Another consideration involves the security characteristics of the Another consideration involves the security characteristics of the
ENRP database. Suppose that some of the PEs register with an ENRP ENRP database. Suppose that some of the PEs register with an ENRP
server using security and some do not. In this case, when a client server using security and some do not. In this case, when a client
requests handle space resolution information from ENRP, it would have requests handle space resolution information from ENRP, it would have
to be informed which entries are "secure" and which are not. to be informed which entries are "secure" and which are not.
2.15.2. Effect 2.15.2. Effect
This would not only complicate the protocol, but actually bring into This would not only complicate the protocol, but actually bring into
question the security and integrity of such a database. What can be question the security and integrity of such a database. What can be
asserted about the security of such a database is a very thorny asserted about the security of such a database is a very thorny
question. question.
2.15.3. Requirement 2.15.3. Requirement
The requirement is that either the entire ENRP server database MUST The requirement is that either the entire ENRP server database MUST
be secure, that is, it has registrations exclusively from PEs that be secure; that is, it has registrations exclusively from PEs that
have used security mechanisms or the entire database MUST be have used security mechanisms, or the entire database MUST be
insecure, that is, registrations are from PEs that have used no insecure; that is, registrations are from PEs that have used no
security mechanisms. ENRP servers that support security MUST reject security mechanisms. ENRP servers that support security MUST reject
any PE server registration that does not use the security mechanisms. any PE server registration that does not use the security mechanisms.
Likewise, ENRP servers that support security MUST NOT accept updates Likewise, ENRP servers that support security MUST NOT accept updates
from other ENRP servers that do not use security mechanisms. TLS is from other ENRP servers that do not use security mechanisms. TLS is
used as the security mechanism so any information not sent using TLS used as the security mechanism so any information not sent using TLS
to a secure ENRP server MUST be rejected. to a secure ENRP server MUST be rejected.
2.16. Cookie mechanism security 2.16. Cookie Mechanism Security
The application layer is out of scope for RSerPool. However, some The application layer is out of scope for RSerPool. However, some
questions have been raised about the security of the cookie mechanism questions have been raised about the security of the cookie
which will be addressed. mechanism, which will be addressed.
Cookies are passed via the ASAP control channel. If TCP is selected Cookies are passed via the ASAP control channel. If TCP is selected
as the transport, then the data and control channel MUST be as the transport, then the data and control channel MUST be
multiplexed. Therefore, the cases: multiplexed. Therefore, the cases:
a. control channel is secured; data channel is not a. control channel is secured; data channel is not
b. data channel is secured; control channel is not b. data channel is secured; control channel is not
are not possible as the multiplexing onto one TCP port results in are not possible, as the multiplexing onto one TCP port results in
security for both data and control channels or neither. security for both data and control channels or neither.
The multiplexing requirement results in the following cases: The multiplexing requirement results in the following cases:
1. the multiplexed control channel-data channel is secure OR 1. the multiplexed control channel-data channel is secure; *or*
2. the multiplexed control channel-data channel is not secured 2. the multiplexed control channel-data channel is not secured.
This applies to cookies in the sense that if you choose to secure This applies to cookies in the sense that, if you choose to secure
your control-data channel, then the cookies are secured. your control-data channel, then the cookies are secured.
A second issue is that the PE could choose to sign and/or encrypt the A second issue is that the PE could choose to sign and/or encrypt the
cookie. In this case, it must share keys and other information with cookie. In this case, it must share keys and other information with
other PEs. This application level state sharing is out of scope of other PEs. This application-level state sharing is out of scope of
RSerPool. RSerPool.
2.17. Potential insider attacks from legitmate ENRP servers 2.17. Potential Insider Attacks from Legitimate ENRP Servers
The previous text does not address all byzantine attacks that could The previous text does not address all byzantine attacks that could
arise from legitimate ENRP servers. True protection against arise from legitimate ENRP servers. True protection against
misbehavior by authentic (but rogue) servers is beyond the capability misbehavior by authentic (but rogue) servers is beyond the capability
of TLS security mechanisms. Authentication using TLS does not of TLS security mechanisms. Authentication using TLS does not
protect against byzantine attacks as authenticated ENRP servers might protect against byzantine attacks, as authenticated ENRP servers
have been maliciously hacked. Protections against insider attacks might have been maliciously hacked. Protections against insider
are generally specific to the attack, so more experimentation is attacks are generally specific to the attack, so more experimentation
needed. For example, the following discusses two insider attacks and is needed. For example, the following discusses two insider attacks
potential mitigations. and potential mitigations.
One issue is that legitimate users may choose to not follow the One issue is that legitimate users may choose not to follow the
proposed policies regarding choice of servers (namely, members in the proposed policies regarding the choice of servers (namely, members in
pool). If the "choose a member at random" policy is employed, then a the pool). If the "choose a member at random" policy is employed,
pool user can always set its "random choices" so that it picks a then a pool user can always set its "random choices" so that it picks
particular pool member. This bypasses the "load sharing" idea behind a particular pool member. This bypasses the "load sharing" idea
the policy. Another issue is that a pool member (or server) may behind the policy. Another issue is that a pool member (or server)
report a wrong policy to a user. may report a wrong policy to a user.
To mitigate the first attack, the protocol may require the pool user To mitigate the first attack, the protocol may require the pool user
to "prove" to the pool member that the pool member was chosen to "prove" to the pool member that the pool member was chosen
"randomly", say by demonstrating that the random choice was the "randomly", say by demonstrating that the random choice was the
result of applying some hash function to a public nonce. Different result of applying some hash function to a public nonce. Different
methods may be appropriate for other member scheduling policies. methods may be appropriate for other member scheduling policies.
To mitigate the second attack, the protocol might require the PE to To mitigate the second attack, the protocol might require the PE to
sign the policy sent to the ENRP server. During pool handle sign the policy sent to the ENRP server. During pool handle
resolution, the signed policy needs to be sent from an ENRP server to resolution, the signed policy needs to be sent from an ENRP server to
skipping to change at page 15, line 31 skipping to change at page 16, line 17
+--------------+----------------------------------------------------+ +--------------+----------------------------------------------------+
| Section 2.1 | ENRP server authenticates the PE. | | Section 2.1 | ENRP server authenticates the PE. |
| Section 2.2 | ENRP server authenticates the PE. | | Section 2.2 | ENRP server authenticates the PE. |
| Section 2.3 | ENRP server authenticates the PE. | | Section 2.3 | ENRP server authenticates the PE. |
| Section 2.4 | ENRP server authenticates the PE. | | Section 2.4 | ENRP server authenticates the PE. |
| Section 2.5 | ENRP servers mutually authenticate. | | Section 2.5 | ENRP servers mutually authenticate. |
| Section 2.6 | PE authenticates the ENRP server. | | Section 2.6 | PE authenticates the ENRP server. |
| Section 2.7 | The PU authenticates the ENRP server. If the | | Section 2.7 | The PU authenticates the ENRP server. If the |
| | authentication fails, it looks for another ENRP | | | authentication fails, it looks for another ENRP |
| | server. | | | server. |
| Section 2.8 | Security protocol which has protection from replay | | Section 2.8 | Security protocol that has protection from replay |
| | attacks. | | | attacks. |
| Section 2.9 | Either notify the application when fail over | | Section 2.9 | Either notify the application when fail over |
| | occurs so the application can take appropriate | | | occurs so the application can take appropriate |
| | action to establish a trusted relationship with PE | | | action to establish a trusted relationship with PE |
| | B OR reestablish the security context | | | B *or* re-establish the security context |
| | transparently. | | | transparently. |
| Section 2.10 | Security protocol which supports integrity | | Section 2.10 | Security protocol that supports integrity |
| | protection. | | | protection. |
| Section 2.12 | Security protocol which supports data | | Section 2.12 | Security protocol that supports data |
| | confidentiality. | | | confidentiality. |
| Section 2.11 | The PU authenticates the ENRP server. If the | | Section 2.11 | The PU authenticates the ENRP server. If the |
| | authentication fails, it looks for another ENRP | | | authentication fails, it looks for another ENRP |
| | server. | | | server. |
| Section 2.13 | ASAP must control the number of endpoint | | Section 2.13 | ASAP must control the number of endpoint |
| | unreachable messages transmitted from the PU to | | | unreachable messages transmitted from the PU to |
| | the ENRP server. | | | the ENRP server. |
| Section 2.14 | ENRP server must control the number of | | Section 2.14 | ENRP server must control the number of |
| | Endpoint_KeepAlive messages to the PE. | | | Endpoint_KeepAlive messages to the PE. |
+--------------+----------------------------------------------------+ +--------------+----------------------------------------------------+
The first four threats combined with the sixth threat result in a
The first four threats, combined with the sixth threat, result in a
requirement for mutual authentication of the ENRP server and the PE. requirement for mutual authentication of the ENRP server and the PE.
To summarize the first twelve threats require security mechanisms To summarize, the first twelve threats require security mechanisms
which support authentication, integrity, data confidentiality and that support authentication, integrity, data confidentiality, and
protection from replay attacks. For RSerPool we need to authenticate protection from replay attacks. For RSerPool, we need to
the following: authenticate the following:
o PU -----> ENRP Server (PU authenticates the ENRP server) o PU -----> ENRP Server (PU authenticates the ENRP server)
o PE <----> ENRP Server (mutual authentication) o PE <----> ENRP Server (mutual authentication)
o ENRP server <-----> ENRP Server (mutual authentication) o ENRP server <-----> ENRP Server (mutual authentication)
Summary by component: Summary by component:
RSerPool client -- mandatory to implement authentication of the ENRP RSerPool client -- mandatory-to-implement authentication of the ENRP
server is required for accurate pool handle resolution. This is server is required for accurate pool handle resolution. This is
to protect against threats from rogue ENRP servers. In addition, to protect against threats from rogue ENRP servers. In addition,
confidentiality, integrity and preventing replay attack are also confidentiality, integrity, and preventing replay attack are also
mandatory to implement to protect from eavesdropping and data mandatory to implement to protect from eavesdropping and data
corruption or false data transmission. Confidentiality is corruption or false data transmission. Confidentiality is
mandatory to implement and is used when privacy is required. mandatory to implement and is used when privacy is required.
PE to ENRP communications -- mandatory to implement mutual PE to ENRP communications -- mandatory-to-implement mutual
authentication, integrity and protection from replay attack is authentication, integrity, and protection from replay attack is
required for PE to ENRP communications. This is to protect the required for PE to ENRP communications. This is to protect the
integrity of the ENRP handle space database. Confidentiality is integrity of the ENRP handle space database. Confidentiality is
mandatory to implement and is used when privacy is required. mandatory to implement and is used when privacy is required.
ENRP to ENRP communications -- mandatory to implement mutual ENRP to ENRP communications -- mandatory-to-implement mutual
authentication, integrity and protection from replay attack is authentication, integrity, and protection from replay attack is
required for ENRP to ENRP communications. This is to protect the required for ENRP to ENRP communications. This is to protect the
integrity of the ENRP handle space database. Confidentiality is integrity of the ENRP handle space database. Confidentiality is
mandatory to implement and is used when privacy is required. mandatory to implement and is used when privacy is required.
4. IANA Considerations 4. Normative References
This document introduces no additional considerations for IANA.
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[I-D.ietf-rserpool-asap] [RFC5352] Stewart, R., Xie, Q., Stillman, M., and M. Tuexen,
Stewart, R., Xie, Q., Stillman, M., and M. Tuexen, "Aggregate Server Access Protocol (ASAP)", RFC 5352,
"Aggregate Server Access Protocol (ASAP)", September 2008.
draft-ietf-rserpool-asap-20 (work in progress), May 2008.
[I-D.ietf-rserpool-enrp] [RFC5353] Xie, Q., Stewart, R., Stillman, M., Tuexen, M., and A.
Xie, Q., Stewart, R., Stillman, M., Tuexen, M., and A.
Silverton, "Endpoint Handlespace Redundancy Protocol Silverton, "Endpoint Handlespace Redundancy Protocol
(ENRP)", draft-ietf-rserpool-enrp-20 (work in progress), (ENRP)", RFC 5353, September 2008.
May 2008.
[I-D.ietf-rserpool-overview] [RFC5351] Lei, P., Ong, L., Tuexen, M., and T. Dreibholz, "An
Lei, P., Ong, L., Tuexen, M., and T. Dreibholz, "An Overview of Reliable Server Pooling Protocols", RFC 5351,
Overview of Reliable Server Pooling Protocols", September 2008.
draft-ietf-rserpool-overview-06 (work in progress),
May 2008.
Authors' Addresses Authors' Addresses
Maureen Stillman (editor) Maureen Stillman, Ed.
Nokia Nokia
1167 Peachtree Court 1167 Peachtree Court
Naperville, IL 60540 Naperville, IL 60540
US USA
Email: maureen.stillman@nokia.com EMail: maureen.stillman@nokia.com
Ram Gopal Ram Gopal
Nokia Siemens Networks Nokia Siemens Networks
12278 Scripps Summit Drive 12278 Scripps Summit Drive
San Diego, CA 92131 San Diego, CA 92131
US USA
Email: ram.gopal@nsn.com EMail: ram.gopal@nsn.com
Erik Guttman Erik Guttman
Sun Microsystems Sun Microsystems
Eichhoelzelstrasse 7 Eichhoelzelstrasse 7
74915 Waibstadt 74915 Waibstadt
DE DE
Email: Erik.Guttman@sun.com EMail: Erik.Guttman@sun.com
Matt Holdrege
Strix Systems
26610 Agoura Road
Suite 110
Calabasas, CA 91302
US
Email: matt@strixsystems.com
Senthil Sengodan Senthil Sengodan
Nokia Siemans Networks Nokia Siemens Networks
6000 Connection Drive 6000 Connection Drive
Irving, TX 75039 Irving, TX 75039
US USA
Email: Senthil.sengodan@nsn.com EMail: Senthil.sengodan@nsn.com
Matt Holdrege
EMail: Holdrege@gmail.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
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