Zero Trust: What It Is and How to Implement It in a Corporate Network
May 9, 2025 · 11 min read · System Networks
Zero Trust is a security architecture built on "never trust, always verify." Instead of treating everything inside the corporate network as safe, every user, device, and request is verified — regardless of location. It is not a product you install; it is a strategy that changes how your organisation thinks about access.
Why the Old Perimeter Model Fails
Three Core Principles
Verify Explicitly
Authenticate and authorise every request using all available data: user identity, location, device, service, data type, anomaly signals. Nothing is trusted by default — not even a system administrator.
Use Least Privilege Access
Grant only the minimum access required to complete a specific task. Access should be time-limited (Just-in-Time) and scope-limited (Just-Enough-Access). Privileged accounts require extra scrutiny.
Assume Breach
Design systems as if an attacker is already inside. Segment the network, encrypt all traffic, maintain detailed logs, and minimise the blast radius when one component is compromised.
ZTNA vs VPN: The Key Difference
| Parameter | Classic VPN | ZTNA |
|---|---|---|
| Access model | Access to entire network | Access only to specific applications |
| Authentication | Once at connection | Continuous, per request |
| Network visibility | User sees entire network | User sees only permitted resources |
| Blast radius if compromised | Entire network | Isolated to specific application |
| User experience | Slower (all traffic through VPN gateway) | Faster direct connection to app |
| Management complexity | Medium | High initially, simpler over time |
Implementation Roadmap (2–3 Years)
Phase 1: Visibility (months 1–3)
- →Inventory all users, devices, applications, and data flows
- →Identify critical assets requiring maximum protection
- →Implement centralised logging — this is the foundation
Phase 2: Identity (months 2–5)
- →Deploy MFA for all users — highest ROI security investment
- →Implement PAM for privileged accounts
- →Introduce RBAC — remove excessive permissions
Phase 3: Network (months 4–9)
- →Network microsegmentation — isolate critical segments
- →Deploy MDM/EMM for device compliance checking
- →Implement ZTNA for remote access
Phase 4: Data (months 6–12)
- →Classify data by sensitivity level
- →Implement DLP for critical data movement control
- →Enable encryption at rest for critical storage
Zero Trust for SMB: 80% Effect, 20% Budget
MFA everywhere
Enable multi-factor authentication for all employees across all key services. Cheapest, highest-impact Zero Trust action.
From ₽500/user/month
Least privilege
Remove excessive rights. Admins should not use privileged accounts for daily tasks. Users should not have local admin rights.
Free (process change)
Network segmentation
Split into minimum 3 segments: users, servers, guests/BYOD. Block direct cross-segment traffic without firewall inspection.
From ₽200,000
Zero Trust architecture design
Zero Trust network design and ZTNA implementation →ZTNA · Microsegmentation · MFA · Russian-certified solutions · FSTEC compliance