ISO/IEC 27033:2010 – Information technology — Security techniques — Network security – Brief Overview of Standard. 


ISO/IEC 27033 is a multi-part standard replacing the five-part ISO/IEC 18028.

Scope and purpose

“The purpose of ISO/IEC 27033 is to provide detailed guidance on the security aspects of the management, operation and use of information system networks, and their inter-connections …”

ISO/IEC 27033 provides detailed guidance on implementing the network security controls that are introduced in ISO/IEC 27002. It applies to the security of networked devices and the management of their security, network applications/services and users of the network, in addition to security of information being transferred through communications links. It is aimed at network security architects, designers, managers and officers.

Part 1: Network security overview and concepts

  • Revised and replaced ISO/IEC 18028 part 1.
  • Provides a roadmap and overview of the concepts and principles underpinning the remaining parts of ISO/IEC 27033.
  • Objective: “to define and describe the concepts associated with, and provide management guidance on, network security. This includes the provision of an overview of network security and related definitions, and guidance on how to identify and analyse network security risks and then define network security requirements. It also introduces how to achieve good quality technical security architectures, and the risk, design and control aspects associated with typical network scenarios and network ‘technology’ areas (which are dealt with in detail in subsequent parts of ISO/IEC 27033). In effect it also provides an overview of the ISO/IEC 27033 series and a ‘road map’ to all other parts”.
  • Provides a glossary of information security terms specific to networking.
  • Provides guidance on a structured process to identify and analyse network security risks and hence define network security control requirements, including those mandated by relevant information security policies.
  • Provides an overview of the controls supporting network technical security architectures and related technical controls, as well as non-technical controls plus other technical controls that are not solely related to network security (thus linking to ISO/IEC 27001ISO/IEC 27002 and ISO/IEC 27005 plus other ISO27k standards as they are released).
  • Explains good practices in respect of network technical security architectures, and the risk, design and control aspects associated with typical network scenarios and network technology areas (expanded in subsequent parts of ISO/IEC 27033 – see below).
  • Briefly addresses the issues associated with implementing and operating network security controls, and the ongoing monitoring and reviewing of their implementation.
  • Extends the security management guidelines provided in ISO/IEC TR 13335 and ISO/IEC 27002 etc. by detailing the specific operations and mechanisms needed to implement network security controls in a wider range of network environments, providing a bridge between general information security management issues and the specifics of implementing largely technical network security controls (e.g. firewalls, IDS/IPS, message integrity controls etc.).
  • Mentions requirements such as non-repudiation and reliability in addition to the classical CIA triad (confidentiality, integrity and availability).
  • Somehow manages to provide a reasonably technical overview of network security with barely any reference to the OSI network stack!

Part 2: Guidelines for the design and implementation of network security

  • Revised and replaced ISO/IEC 18028 part 2.
  • Scope: planning, designing, implementing, and documenting network security.
  • Objective: “to define how organisations should achieve quality network technical security architectures, designs and implementations that will ensure network security appropriate to their business environments, using a consistent approach to the planning, design and implementation of network security, as relevant aided by the use of models/frameworks. (In this context, a model/framework is used to outline a representation or description showing the structure and high level workings of a type of technical security architecture/design)” [quoted from the FCD of 27033-1].
  • Defines a network security architecture for providing end-to-end network security. The architecture can be applied to various kinds of networks where end-to-end security is a concern and independently of the network’s underlying technology.
  • Serves as a foundation for detailed recommendations on end-to-end network security.
  • Covers risks, design, techniques and control issues.
  • Refers to other parts of ISO/IEC 27033 for more specific guidance.

Part 3: Reference networking scenarios — threats, design techniques and control issues

  • Objective: “to define the specific risks, design techniques and control issues associated with typical network scenarios” .
  • Discusses threats, specifically, rather than all the elements of risk.
  • Refers to other parts of ISO/IEC 27033 for more specific guidance.

Part 4: Securing communications between networks using security gateways

  • Revision of ISO/IEC 18028 part 3 and possibly ISO/IEC 18028 part 4.
  • Provides an overview of security gateways through a description of different architectures.
  • Guideline on securing communications between networks through gateways, firewalls, application firewalls, Intrusion Protection System [sicetc. in accordance with a policy, including identifying and analysing network security threats, defining security control requirements, and designing, implementing, operating, monitoring and reviewing the controls.
  • Outlines how security gateways analyse and control network traffic through:
    • Packet filtering;
    • Stateful packet inspection;
    • Application proxy (application firewalls);
    • Network address translation NAT;
    • Content analysis and filtering.
  • Guides the selection and configuration of security gateways, choosing the right type of architecture for a security gateway which best meets the security requirements of an organisation.
  • Refers to various kinds of firewall as examples of security gateways. [Firewall is a commonplace term of art that is curiously absent from ISO/IEC 27000, ISO/IEC 27002 and is not defined explicitly in this standard either].

Part 5: Securing communications across networks using Virtual Private Networks (VPNs)

  • Revision of ISO/IEC 18028 part 5.
  • Objective: to provide “guidelines for the selection, implementation and monitoring of the technical controls necessary to provide network security using Virtual Private Network (VPN) connections to interconnect networks and connect remote users to networks”.
  • Extends the IT security management guidelines of ISO/IEC TR 13335 by detailing the specific operations and mechanisms needed to implement network security safeguards and controls in a wider range of network environments, providing a bridge between general IT security management issues and network security technical implementations.
  • Provides guidance for securing remote access over public networks.
  • Gives a high-level, incomplete assessment of the threats to VPNs (i.e. it mentions the threats of intrusion and denial of service but not unauthorized monitoring/interception, traffic analysis, data corruption, insertion of bogus traffic, various attacks on VPN end points, malware, masquerading/identity theft, insider threats etc., although these are mentioned or at least hinted-at later under security requirements).
  • Introduces different types of remote access including protocols, authentication issues and support when setting up remote access securely.
  • Intended to help network administrators and technicians who plan to make use of this kind of connection or who already have it in use and need advice on how to set it up securely and operate it securely.

Part 6: Securing wireless IP network access

  • Objective: “to define the specific risks, design techniques and control issues for securing IP wireless networks. [This part] is relevant to all personnel who are involved in the detailed planning, design and implementation of security for wireless networks (for example, network architects and designers, network managers, and network security officers)”.
  • This is a generic wireless network security standard offering basic advice for WiFi, Bluetooth, 3G and other wireless networks.
  • The standard uses the term “wire line network”, more commonly known as a wired network.
  • The standard repeatedly refers to “access network”, a curious term that is not defined (aside from Radio Access Network). It seems to mean “network” but without a definition, I cannot tell for sure.
  • The standard indicates that encryption is an integrity control, whereas normally other cryptographic controls and protocols provide the integrity functions, while encryption provides confidentiality.
  • Similarly to Part 7, this part lists a number of “threats” which are, in fact, attack modes or incident scenarios. The list would have been more useful if the standard systematically addressed each of them, explaining how certain controls mitigate them.

Part 7: Guidelines for network virtualization security

  • This standard started out as ISO/IEC 5188 before being adopted into the ISO27k family.
  • Part 7 is at Committee Draft stage, progressing  well. It is not due to be published until 2024.
  • The working title is: Information Technology — Network Security — Part 7: Guidelines for network virtualization security.
  • The draft standard outlines some “security threats” or “security issues” – not information risks as such, more like generic examples of types of incident such as “Insider attacks: an administrator tampers image or changes security configurations”… The draft misuses several risk-related terms – perhaps just a language issue but I suspect the authors may not fully grasp the fundamental concepts. It looks as if the published standard will not explain which information security controls address the “security threats/issues”, nor which information risks the suggested information security controls are intended to mitigate: there is no cross-referencing between the two, hence it is unclear how users are meant to identify, select or prioritise whichever controls are most appropriate for their situations. So much for the “implementation guidelines”!

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