As businesses become more concerned about cybersecurity, security teams’ requirement for network access and data visibility has expanded. Using the zero trust security concept, organizations can gain insight into their network access and data. It allows network users’ identities to be validated, user access and device control, and unauthorized access to be prevented.

The zero trust security model is a top cybersecurity design because it defaults devices to the least privileged user roles within an organization. This blog post will go through what zero trust security architecture is, how it works, zero trust security use cases, and its concepts.

Zero trust security architecture is a strategic approach to cybersecurity that eliminates implicit trust and continually validates the digital interactions of all parties. A zero trust architecture follows the “never trust, always verify” principle and enforces access policies based on context, including the user’s role and location, their device, and the data they are requesting. This approach has many benefits, such as simpler network infrastructure, better user experience, increased cybersecurity, and improved IT governance.

A well-tuned zero trust security architecture leads to simpler network infrastructure, better user experience, and improved cyber threat defense. Additionally, zero trust creates a culture of security where everyone is accountable for their actions, and access control is consistent across teams and organizations.

What is Zero Trust Network Access (ZTNA)?

Zero Trust Network Access (ZTNA) is the main technology that enables organizations to implement Zero Trust security. Similar to a software-defined perimeter (SDP), ZTNA conceals most infrastructure and services, setting up one-to-one encrypted connections between devices and the resources they need.

Any organization that relies on a network and stores digital data will probably consider using a Zero Trust architecture. But some of the most common use cases for Zero Trust include:

Replacing or augmenting a VPN: Many organizations rely on VPNs to protect their data, but as described above, VPNs are often not ideal for defending against today’s risks.

Securely supporting remote work: While VPNs create bottlenecks and can slow productivity for remote workers, Zero Trust can extend secure access control to connections from anywhere.

Access control for cloud and multi-cloud: A Zero Trust network verifies any request, no matter its source or destination. It can also help reduce the use of unauthorized cloud-based services (a situation called “shadow IT”) by controlling or blocking the use of unsanctioned apps.

Onboarding third parties and contractors: Zero Trust can quickly extend restricted, least-privilege access to external parties, who typically use computers that are not managed by internal IT teams.

Rapidly onboarding new employees: Zero Trust networks can also facilitate quickly onboarding new internal users, making them a good fit for fast-growing organizations. In contrast, a VPN may need to add more capacity to accommodate large numbers of new users.

How Zero Trust Security Works

Assume everything is hostile by default, the fundamental idea of zero trust. It’s a significant break from the centralized data center and secure network perimeter network security paradigm, which has been in use since the ’90s. To create restrictions and verify what’s trusted inside the network, these network architectures usually depend on authorized IP addresses, ports, and protocols to establish access control.

A zero-trust strategy, on the other hand, considers all traffic to be hostile, no matter how it got there. Workloads, for example, are unable to communicate until they have been validated by a set of authentication attributes, such as a fingerprint.

Due to the environment-agnostic nature of the protection, the zero trust model secures services and applications regardless of cross-network communication. This does not require any policy updates or architectural changes.

Types of ZTA Models And Their Benefits

The National Cyber Security Center of Excellence recommends four main features of a zero trust architecture:

1. Identify—creates an inventory of systems, software, and other resources, classifies them, and sets baselines to allow for detecting anomalies.
2. Protect—authentication and authorization processing. Zero trust protection includes policy-based resource authentication and configuration, as well as software, firmware, and hardware integrity checks.
3. Detect—identifies anomalies and suspicious events, by continuously monitoring network activity to proactively detect potential threats.
4. Respond—Once a threat is detected, handles threat containment and mitigation.

These capabilities are typically implemented by several IT and security solutions, which work together to create a zero trust environment.

With the above components, you can achieve the following workflow:

1. Users sign into corporate systems using multi factor authentication (MFA), verifying their identity over a secure channel.
2. User accounts are granted access only to the specific applications and network resources they actually need (least privileged access model)
3. User sessions are continuously monitored for unusual or malicious activity
4. When potential malicious activity is detected, threat response occurs in real time

The same workflow is applied to all users and resources in the organization, providing tight, granular control over access.

There are many ways to implement a zero trust architecture in an organization. Here are a few primary options, each of which places emphasis on different tenets of the zero trust model.

ZTA with Enhanced Identity Governance

This option makes the identity of the actor an important factor in policymaking. You define the access conditions for each enterprise resource based on its identity and assigned attributes of the user or system accessing the resource. The main requirement is to give each user or system appropriate access to resources, without giving access to any unnecessary systems.

ZTA with Micro-Segmentation

This option implements zero trust by placing individuals or groups of resources on different network segments, with secure gateways between segments. Organizations can use network equipment like routers, switches, next-generation firewalls (NGFW), or software agents, to act as a policy enforcement point (PEP) that protects groups of resources.

ZTA with Software Defined Network Perimeters

This option leverages an overlay network, typically at layer 7 of the OSI model (the application layer), but may also be lower down in the network stack. This method is known as Software Defined Perimeter (SDP) because it usually leverages Software Defined Networking (SDN) technology, in which networks are managed using flexible, virtualized appliances.

Best Practices For Implementing ZTA

Know your Architecture

When building a zero trust architecture, it is extremely important to map out your network topology and know your assets. You need to understand who are your users, what devices they are using, and which services and data they are accessing.

Read Also: Cryptography: The Science Behind Data Protection

Pay special attention to components that use the network. Consider any network as hostile—whether it is your local network or an unsecured public network. Also take into account existing services that were not designed for a zero trust architecture, and may not be able to defend themselves.

Create a Strong Device Identity

Device identity is a cornerstone of a zero trust architecture. It is the basis for authentication, authorization, and other security mechanisms. It must be strong and unique.

The device identity must be:

Attached to the device rather than to the user. It should be possible to identify devices even if they are not connected to a network or are behind a NAT device.

• Verifiable by the network. A device should not be able to claim multiple identities or identities that do not belong to it.
• Persistent and remain unchanged even if the device is repurposed or replaced.
• Verifiable over time. It should be possible to check if a device is still in use or has been decommissioned.
• Verifiable across networks. The same device should be able to prove its identity when connecting from different networks, including public ones.

Create a Secure Communication Channel

Communication channels within a zero trust architecture must be secure and trusted. They need to protect against eavesdropping, replay attacks, message modification, and other threats. The communication channel between any two devices needs to provide confidentiality, integrity, and authenticity of messages exchanged between them. It may also need to support non-repudiation for certain use cases.

Communication channels may also need to support:

• Protection against denial of service (DoS) attacks
• Authorization of user requests—for example, when a user attempts to access data they do not have permission for
• Authorization of devices—for example, when a client attempts to connect from an unauthorized device
• Time-controlled access based on time of day or location of the user

Use Network Segmentation

Any zero trust architecture relies heavily on network segmentation and security controls between network segments. These are used to protect sensitive data and services from unauthorized access.

Segmentation can be implemented using VLANs, firewalls, and other types of security controls such as IDS/IPS. It is important to implement these security controls in a way that protects your assets from both internal and external threats.

• Monitor network traffic and connected devices: Visibility is crucial in order for users and machines to be verified and authenticated.
• Keep devices updated: Vulnerabilities need to be patched as quickly as possible. Zero Trust networks should be able to restrict access to vulnerable devices (another reason why monitoring and validation are key).
• Apply the principle of least privilege for everyone in the organization: From executives to IT teams, everyone should have the least amount of access they need. This minimizes the damage if an end user account becomes compromised.
• Partition the network: Breaking up the network into smaller chunks helps ensure breaches are contained early, before they can spread. Microsegmentation is an effective way to do this.
• Act as if the network perimeter did not exist: Unless a network is completely air-gapped (a rarity), the points where it touches the Internet or the cloud are probably too numerous to eliminate.
• Use security keys for MFA: Hardware-based security tokens are demonstrably more secure than soft tokens like one-time passcodes (OTPs) sent via SMS or email.
• Incorporate threat intelligence: Since attackers are constantly updating and refining their tactics, subscribing to the latest threat intelligence data feeds is critical for identifying threats before they spread.
• Avoid motivating end users to circumvent security measures: Just as overly strict password requirements incentivize users to recycle the same passwords over and over, forcing users to re-authenticate once an hour via multiple identity factors may be too much, ironically decreasing security. Always keep the end user’s needs in mind.

What are the Main Principles Behind Zero Trust?

Continuous monitoring and validation

The philosophy behind a Zero Trust network assumes that there are attackers both within and outside of the network, so no users or machines should be automatically trusted. Zero Trust verifies user identity and privileges as well as device identity and security. Logins and connections time out periodically once established, forcing users and devices to be continuously re-verified.

Least privilege

Another principle of Zero Trust security is least-privilege access. This means giving users only as much access as they need, like an army general giving soldiers information on a need-to-know basis. This minimizes each user’s exposure to sensitive parts of the network.

Implementing the least privilege involves careful management of user permissions. VPNs are not well-suited for least-privilege approaches to authorization, as logging in to a VPN gives a user access to the whole connected network.

Device access control

In addition to controls on user access, Zero Trust also requires strict controls on device access. Zero Trust systems need to monitor how many different devices are trying to access their network, ensure that every device is authorized, and assess all devices to make sure they have not been compromised. This further minimizes the attack surface of the network.

Microsegmentation

Zero Trust networks also utilize microsegmentation. Microsegmentation is the practice of breaking up security perimeters into small zones to maintain separate access for separate parts of the network. For example, a network with files living in a single data center that utilizes microsegmentation may contain dozens of separate, secure zones. A person or program with access to one of those zones will not be able to access any of the other zones without separate authorization.

Preventing lateral movement

In network security, “lateral movement” is when an attacker moves within a network after gaining access to that network. Lateral movement can be difficult to detect even if the attacker’s entry point is discovered because the attacker will have gone on to compromise other parts of the network.

Zero Trust is designed to contain attackers so that they cannot move laterally. Because Zero Trust access is segmented and has to be re-established periodically, an attacker cannot move across to other microsegments within the network. Once the attacker’s presence is detected, the compromised device or user account can be quarantined, cut off from further access. (In a castle-and-moat model, if lateral movement is possible for the attacker, quarantining the original compromised device or user has little to no effect, since the attacker will already have reached other parts of the network.)

Multi-factor authentication (MFA)

Multi-factor authentication (MFA) is also a core value of Zero Trust security. MFA means requiring more than one piece of evidence to authenticate a user; just entering a password is not enough to gain access. A commonly seen application of MFA is the 2-factor authorization (2FA) used on online platforms like Facebook and Google. In addition to entering a password, users who enable 2FA for these services must also enter a code sent to another device, such as a mobile phone, thus providing two pieces of evidence that they are who they claim to be.