Zero trust security model

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The zero trust security model, also known as zero trust architecture (ZTA), and sometimes known as perimeterless security, describes an approach to the strategy, design and implementation of IT systems. The main concept behind the zero trust security model is "never trust, always verify", which means that users and devices should not be trusted by default, even if they are connected to a permissioned network such as a corporate LAN and even if they were previously verified.

ZTA is implemented by establishing strong identity verification, validating device compliance prior to granting access, and ensuring least privilege access to only explicitly-authorized resources. Most modern corporate networks consist of many interconnected zones, cloud services and infrastructure, connections to remote and mobile environments, and connections to non-conventional IT, such as IoT devices.

The reasoning for zero trust is that the traditional approach – trusting users and devices within a notional "corporate perimeter", or users and devices connected via a VPN – is not sufficient in the complex environment of a corporate network. The zero trust approach advocates mutual authentication, including checking the identity and integrity of users and devices without respect to location, and providing access to applications and services based on the confidence of user and device identity and device health in combination with user authentication.[1] The zero trust architecture has been proposed for use in specific areas such as supply chains.[2][3]

The principles of zero trust can be applied to data access, and to the management of data. This brings about zero trust data security where every request to access the data needs to be authenticated dynamically and ensure least privileged access to resources. In order to determine if access can be granted, policies can be applied based on the attributes of the data, who the user is, and the type of environment using Attribute-Based Access Control (ABAC). This zero-trust data security approach can protect access to the data.[4]


In April 1994, the term "zero trust" was coined by Stephen Paul Marsh in his doctoral thesis on computer security at the University of Stirling. Marsh's work studied trust as something finite that can be described mathematically, asserting that the concept of trust transcends human factors such as morality, ethics, lawfulness, justice, and judgement.[5]

The problems of the Smartie or M&M model of the network (the precursor description of de-perimeterisation) was described by a Sun Microsystems engineer in a Network World article in May 1994, who described firewalls' perimeter defence, as a hard shell around a soft centre, like a Cadbury Egg.[6]

In 2001 the first version of the OSSTMM (Open Source Security Testing Methodology Manual) was released and this had some focus on trust. Version 3 which came out around 2007 has a whole chapter on Trust which says "Trust is a Vulnerability" and talks about how to apply the OSSTMM 10 controls based on Trust levels.

In 2003 the challenges of defining the perimeter to an organisation's IT systems was highlighted by the Jericho Forum of this year, discussing the trend of what was then given the name "de-perimeterisation".

In response to Operation Aurora, a Chinese APT attack throughout 2009, Google started to implement a zero-trust architecture referred to as BeyondCorp.

In 2010 the term zero trust model was used by analyst John Kindervag of Forrester Research to denote stricter cybersecurity programs and access control within corporations.[7][8][9]

However, it would take almost a decade for zero trust architectures to become prevalent, driven in part by increased adoption of mobile and cloud services. [citation needed]

In 2018, work undertaken in the United States by cybersecurity researchers at NIST and NCCoE led to the publication of NIST SP 800-207 – Zero Trust Architecture.[10][11] The publication defines zero trust (ZT) as a collection of concepts and ideas designed to reduce the uncertainty in enforcing accurate, per-request access decisions in information systems and services in the face of a network viewed as compromised. A zero trust architecture (ZTA) is an enterprise's cyber security plan that utilizes zero trust concepts and encompasses component relationships, workflow planning, and access policies. Therefore, a zero trust enterprise is the network infrastructure (physical and virtual) and operational policies that are in place for an enterprise as a product of a zero trust architecture plan.

There are several ways to implement all the tenets of ZT; a full ZTA solution will include elements of all three:

  • Using enhanced identity governance and policy-based access controls.
  • Using micro-segmentation
  • Using overlay networks or software-defined perimeters

In 2019 the United Kingdom National Cyber Security Centre (NCSC) recommended that network architects consider a zero trust approach for new IT deployments, particularly where significant use of cloud services is planned.[12] An alternative but consistent approach is taken by NCSC, in identifying the key principles behind zero trust architectures:

  • Single strong source of user identity
  • User authentication
  • Machine authentication
  • Additional context, such as policy compliance and device health
  • Authorization policies to access an application
  • Access control policies within an application

See also[edit]


  1. ^ "Mutual TLS: Securing Microservices in Service Mesh". The New Stack. 2021-02-01. Retrieved 2021-02-20.
  2. ^ Collier, Zachary A.; Sarkis, Joseph (2021-06-03). "The zero trust supply chain: Managing supply chain risk in the absence of trust". International Journal of Production Research. 59 (11): 3430–3445. doi:10.1080/00207543.2021.1884311. ISSN 0020-7543. S2CID 233965375.
  3. ^ do Amaral, Thiago Melo Stuckert; Gondim, João José Costa (November 2021). "Integrating Zero Trust in the cyber supply chain security". 2021 Workshop on Communication Networks and Power Systems (WCNPS). pp. 1–6. doi:10.1109/WCNPS53648.2021.9626299. ISBN 978-1-6654-1078-6. S2CID 244864841.
  4. ^ Yao, Qigui; Wang, Qi; Zhang, Xiaojian; Fei, Jiaxuan (2021-01-04). "Dynamic Access Control and Authorization System based on Zero-trust architecture". 2020 International Conference on Control, Robotics and Intelligent System. CCRIS '20. New York, NY, USA: Association for Computing Machinery. pp. 123–127. doi:10.1145/3437802.3437824. ISBN 978-1-4503-8805-4. S2CID 230507437.
  5. ^ Marsh, Stephen (1994), Formalising Trust as a Computational Concept, p. 56, retrieved 2022-07-22
  6. ^ "Internet hackers beware: corporate LANs protected". Network World. IDG Network World Inc. 23 May 1994. ISSN 0887-7661 – via Google Books.
  7. ^ Loten, Angus (2019-05-01). "Akamai Bets on 'Zero Trust' Approach to Security". Wall Street Journal. Retrieved 2022-02-17.
  8. ^ Higgins, Kelly Jackson. "Forrester Pushes 'Zero Trust' Model For Security". Dark Reading. Informa. Archived from the original on 26 August 2021. Retrieved 2022-02-17.
  9. ^ Kindervag, John (2010-11-05). "Build Security Into Your Network's DNA: The Zero Trust Network Architecture" (PDF). Forrester Research. Retrieved 2022-07-22.
  10. ^ National Cybersecurity Center of Excellence. "Implementing a Zero Trust Architecture". NIST. Retrieved 2022-07-22.
  11. ^ Rose, Scott; Borchert, Oliver; Mitchell, Stu; Connelly, Sean. "Zero Trust Architecture" (PDF). NIST. Retrieved 2020-10-17.
  12. ^ "Network architectures". Retrieved 2020-08-25.