SIST-TP ETSI/TR 101 510-1 V1.1.1:2005

• Abstract:

  To consider Security issues which arise from the interconnection of two or more INs, when the interface of interconnection is from the SCF or SDF in one network to an SSF in another network. This work will be fed in to a revision of WI NA-061204. The proposed use of such interfaces in CAMEL phase 1, and other talk of such interfaces being used prompts careful study of the security implications, which have not previously been addressed. Reference documents: DTR/NA-061203 and DTR/NA-061204.

• Status: Published
• Publication Date: 31-Dec-2004
• ICS: 33.040.35 - Telephone networks
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jan-2005
• Due Date: 01-Jan-2005
• Completion Date: 01-Jan-2005
• Ref Project: ETSI TR 101 510-1 V1.1.1 (2000-01) - Intelligent Network (IN); Security aspects of Switching Control Function (SCF) - Service Switching Function (SSF) interconnection between networks; Part 1: Capability Set 1 (CS1) based operations

SIST-TP ETSI/TR 101 510-1 V1.1.1:2005 is the Slovenian publication of an ETSI Technical Report on the security aspects of Intelligent Network (IN) interconnection between networks. It focuses on Capability Set 1 (CS1) based operations, especially the CAMEL phase 1 subset, and describes the main threats and countermeasures for engineers, operators, and security planners working on SCF-SSF signaling.

What does SIST-TP ETSI/TR 101 510-1 V1.1.1:2005 specify?

SIST-TP ETSI/TR 101 510-1 V1.1.1:2005 describes security issues that arise when two or more IN networks interconnect through an SCF or SDF in one network and an SSF in another. The report is limited to SCF-SSF interconnection and, for the present version, to CAMEL phase 1 operations within CS1.

The document is organized into:

• Clause 1, Scope
• Clause 2, References
• Clause 3, Definitions and abbreviations
• Clause 4, Functionality
• Clause 5, Security considerations of operations
• Clause 6, Security countermeasures
• Bibliography and history

In practice, this means the report is not a general IN overview. It concentrates on the inter-domain control path, where security and authorization matter because one network can influence call control resources in another.

What are the key requirements of SIST-TP ETSI/TR 101 510-1 V1.1.1:2005?

The report’s technical focus is the limited CS1 operation set used for SCF-SSF interconnection. Table 1 lists seven operations and their direction between SSF and SCF, which helps operators identify exactly which signaling messages need protection.

Scope of the interconnection

Clause 4 explains the roles of the SSF and SCF in call control. The SSF extends call control with service triggers and signaling to the SCF, while the SCF directs call handling and may interact with other IN entities such as the SDF and SRF. In practice, the reader learns which component originates control and which component must trust incoming instructions.

Operation-specific security concerns

Clause 5 associates security concerns with individual CS1 operations:

• initialDP can be hijacked if another SCF takes over an active signaling session.
• connect and releaseCall must stay within the SCF’s jurisdiction, because unauthorized use can consume resources or tear down calls.
• requestReportBCSMEvent can expose call-traffic monitoring and consume network resources.
• continue can disturb the call state model if sent by an unauthorized SCF.
• activityTest consumes processing and bandwidth because the SSF must respond.
• eventReportBCSM is noted as having no identified security issues in this report.

This matters because the report distinguishes between message types that mainly affect confidentiality, those that affect availability, and those that affect call-state integrity.

Security countermeasures

Clause 6 groups the countermeasures by security property:

• Topology - limit interconnection paths and expose only the minimum needed functionality.
• Authentication - verify the originator and protect authentication data in transit, processing, and storage.
• Access control - protect all SSF and SCF interfaces and auditing functions.
• Integrity - detect message changes.
• Confidentiality - protect sensitive data, for example by encryption.
• Non repudiation - make actions provable in case of disputes.
• Accountability and auditing - record security events with enough detail and keep the records intact.
• Network security management - detect and respond to denial of service and congestion.
• Testing and operation maintenance - include security in interoperability testing and operating procedures.

For a buyer or implementer, this section is the practical checklist: it shows which protections need to be built into the interconnect and which procedures need to be covered in testing and operations.

What terms does SIST-TP ETSI/TR 101 510-1 V1.1.1:2005 define?

• Service Switching Function (SSF) - The function that extends call control, manages signaling with the SCF, and applies SCF instructions to call processing.
• Service Control Function (SCF) - The function that commands call control functions and may use other IN entities to obtain logic or data.
• Capability Set 1 (CS1) - The IN capability set used here as the basis for the interconnection operations under study.
• CAMEL (Customized Applications for Mobile Enhanced Logic) - The mobile application context used in this report for SCF-SSF interconnection.
• Basic Call State Model (BCSM) - The call-state model used to detect and report call-related events.
• Trigger Detection Point - Request (TDP-R) - The point in the BCSM where the SSF detects a trigger and asks the SCF for instructions.
• Intelligent Network Application Part (INAP) - The protocol family associated with IN service control signaling.

Who uses SIST-TP ETSI/TR 101 510-1 V1.1.1:2005?

This report is used by telecommunications network operators, mobile network vendors, IN platform designers, and security architects who work with SCF-SSF interconnection. It is also relevant to interoperability testers and operations teams because it highlights the signaling operations, attack paths, and operational controls that need to be covered in testing, access control, auditing, and incident handling.

Which standards are used with SIST-TP ETSI/TR 101 510-1 V1.1.1:2005?

Standard or document	Contribution
ITU-T Recommendation Q.1228 (1997)	Gives the IN CS2 interface background used in the report’s functional descriptions and terminology.
ETSI TR 101 510-2	The companion part of the same multi-part report, covering CS2 based operations.
DTR/NA-061203	Named in the scope as a reference document linked to the work on IN security interconnection.
DTR/NA-061204	Named in the scope as a reference document that the work is intended to feed into.

What does the SIST-TP ETSI/TR 101 510-1 V1.1.1:2005 document contain?

The document contains a short structural overview of SSF, SCF, and their interconnection, followed by a table of the seven CS1 operations used between them. It gives a brief function description and security note for each operation, which is useful for threat analysis and implementation review.

It also includes a figure showing an internetworking scenario across two domains, and a countermeasure section organized by security property and operational concern. The bibliography points to related IN, INAP, and security documents that support design, testing, and service interconnect planning.

SLOVENSKI STANDARD
01-januar-2005
Inteligentno omrežje (IN) – Varnostni vidiki funkcije krmiljenja storitev (SCF) –
Funkcija komutacije storitve (SSF) medsebojnega povezovanja omrežij – 1. del:
Operacije na podlagi prvega nabora zmožnosti (CS1)
Intelligent Network (IN); Security aspects of Switching Control Function (SCF) - Service
Switching Function (SSF) interconnection between networks; Part 1: Capability Set 1
(CS1) based operations
Ta slovenski standard je istoveten z: TR 101 510-1 Version 1.1.1
ICS:
33.040.35 Telefonska omrežja Telephone networks
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Technical Report
Intelligent Network (IN);
Security aspects of Switching Control Function (SCF) -
Service Switching Function (SSF)
interconnection between networks;
Part 1: Capability Set 1 (CS1) based operations

2 ETSI TR 101 510-1 V1.1.1 (2000-01)
Reference
DTR/SPAN-061208-1
Keywords
CS1,IN, interworking, security
ETSI
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The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2000.
All rights reserved.
ETSI
3 ETSI TR 101 510-1 V1.1.1 (2000-01)
Contents
Intellectual Property Rights.4
Foreword .4
Introduction .4
1 Scope.5
2 References.5
3 Definitions and abbreviations .5
3.1 Definitions.5
3.2 Abbreviations .6
4 Functionality .6
4.1 SSF .6
4.2 SCF.6
4.3 SSF-SCF Interconnection.7
5 Security considerations of operations .8
5.1 initialDP .8
5.2 connect .8
5.3 releaseCall .8
5.4 eventReportBCSM .8
5.5 requestReportBCSMEvent .8
5.6 continue .9
5.7 activityTest .9
6 Security countermeasures.9
6.1 Topology .9
6.2 Authentication .9
6.3 Access control .9
6.4 Integrity .10
6.5 Confidentiality.10
6.6 Non Repudiation.10
6.7 Accountability and auditing.10
6.8 Network security management .10
6.9 Testing and operation maintenance .10
Bibliography.11
History.12
ETSI
4 ETSI TR 101 510-1 V1.1.1 (2000-01)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server
(http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Services and Protocols for Advanced
Networks (SPAN).
The present document is part 1 of a multi-part TR covering the Intelligent Network (IN); Security aspects of Switching
Control Function (SCF) - Service Switching Function (SSF) interconnection between networks, as identified below:
Part 1: "Capability Set 1 (CS1) based operations".
Part 2: "Capability Set 2 (CS2) based operations".
Introduction
Under IN CS1 & CS2, the IN SCP to SSP relationship, or Service Control to Switch, is confined to a single network operator's
domain and may actually be physically co-located as an SSCP. To optimize performance, the switch requires little security,
particularly if implemented within a `single unit` or SSCP. By not using the local processor for security, switch performance
may be optimized toward call processing with security and network protection measures provided at the Service Control Point.
In the case of inter-connected networks, direct implementation of the Inter-network Control to Switch relationship would require
appropriate security and authentication measures to be provided and managed at each SSF.
Within a single network, potential conflict between multiple SCFs is avoided by their management within a common domain.
When two networks are interconnected two (or more) SCFs in different domains can potentially control the same resource
(SSF). Then some secure resource allocation and management procedure must be deployed. Suitable mechanisms have not yet
been standardized. Network operators may prefer the option of utilizing the established inter-network SCF to SCF security
procedures and route inter-network service switching signalling messages via each Network's Service Control Point. In this case
appropriate security and authentication measures would be provided and managed at each SCF.
ETSI
5 ETSI TR 101 510-1 V1.1.1 (2000-01)
1 Scope
The present document describes security aspects in conjunction with the interconnection of two IN structured networks.
The present document concentrates on the SCF - SSF interconnection.
The purpose of the present document is to describe the security aspects of interconnection of SCF to SSF. The
operations considered in this interconnection are a subset of CS1. For the time being CAMEL is the only application of
SCF - SSF interconnection, therefore the present document considers only CAMEL phase 1 operations. A later edition
may also consider other CS1 operations.
Future parts of the present document will investigate the security aspects of operation sets that are a subset of CS2 and
CS3.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
• A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
[1] ITU-T Recommendation Q.1228 (1997): "CD-ROM - Interface Recommendation for intelligent
network Capability Set 2".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
masquerade ("spoofing"): pretence of an entity to be a different entity. This may be a basis for other threats like
unauthorized access or forgery.
unauthorized access: entity attempts to access data in violation to the security policy in force.
eavesdropping: breach of confidentiality by monitoring communication.
loss or corruption of information: integrity of data (transferred) is compromised by unauthorized deletion, insertion,
modification, reordering, replay or delay.
replay of information: repetition of previously valid commands and responses with the intention of corrupting service
or causing an overload.
repudiation: denial by one of the entities involved in a communication of having participated in all or part of the
communication.
forgery: entity fabricates information and claims that such information was received from another entity or sent to
another entity.
denial of service: prevention of authorized access to resources or the delaying of time critical operations.
ETSI
6 ETSI TR 101 510-1 V1.1.1 (2000-01)
unauthorized activity: attacker performs activities for which he has no pe
...