Image by: Stefan Coders

The evolving threat landscape: Why traditional VPNs fall short

Did you know 68% of organizations experienced VPN-related breaches in 2023? As remote work expands, IT managers grapple with outdated security models. Traditional SSL/TLS VPNs create a “trust but verify” environment where authenticated users gain broad network access – essentially becoming insider threats the moment credentials are compromised. This flat-network approach enables dangerous lateral movement, letting attackers pivot freely after initial access. Consider the Colonial Pipeline breach: attackers entered through a legacy VPN, then moved unimpeded for days.

Performance bottlenecks compound these risks. During peak usage, VPN concentrators become choke points. A global survey found 74% of enterprises report VPN latency issues degrading productivity. As cloud adoption accelerates, backhauling traffic through data centers creates unsustainable latency. For example, accessing Salesforce via a corporate VPN adds 120+ ms latency versus direct connections.

The lateral movement epidemic

Flat networks enabled by VPNs are cybercriminals’ playgrounds:

• Compromised credentials grant access to entire network segments
• Minimal microsegmentation allows ransomware to spread unchecked
• Legacy systems remain visible to authenticated users

“VPNs are like giving someone a master key to your building after checking their ID once,” notes cybersecurity expert Mikko Hyppönen. “Zero Trust treats every room as a separate fortress.”

Zero Trust 101: Principles and core components

Born from Forrester’s landmark 2010 research, Zero Trust Network Access (ZTNA) operates on “never trust, always verify” principles. Unlike VPNs’ network-centric model, ZTNA focuses on granular application-level access. Users gain access only to authorized resources after continuous authentication checks, significantly reducing attack surfaces.

Core ZTNA components include:

1. Identity verification: Multi-factor authentication (MFA) and device posture checks before connection
2. Context-aware policies: Dynamic access rules based on user role, location, and risk profile
3. Encrypted micro-tunnels: Individual connections per application, not full network access
4. Broker architecture: Cloud-based controllers that never expose applications to the open internet

This framework eliminates the concept of “internal” networks. A Gartner study shows ZTNA adopters reduce breach impact by 80% by containing threats to isolated application segments. For compliance-heavy industries, ZTNA provides detailed access logs – something VPNs struggle to deliver at scale.

Head-to-head comparison: Security, performance, and scalability

When evaluating SSL/TLS VPN vs Zero Trust, three dimensions demand scrutiny: security posture, user experience, and growth capacity. Consider how each handles lateral movement – ZTNA’s microsegmentation inherently contains threats, while VPNs leave entire subnets vulnerable.

Performance diverges dramatically at scale. VPNs require costly hardware upgrades for every 500 concurrent users, while ZTNA solutions like Zscaler Private Access scale elastically. In a 10,000-user deployment, ZTNA reduces bandwidth costs by 40% by eliminating backhaul.

The user experience factor

Modern workforces demand frictionless access. ZTNA’s clientless browser access beats VPN client installations – a critical advantage for contractors. One Fortune 500 company cut helpdesk tickets by 65% after switching to ZTNA, as detailed in this migration case study.

Cost considerations and hybrid deployment models

Transitioning from VPN to ZTNA requires strategic financial analysis. While VPNs have lower initial costs ($5K appliances vs $30K+ ZTNA licenses), TCO flips at scale. For 2,000 users, VPNs incur $185K/year in hardware, bandwidth, and breach-related costs versus ZTNA’s $120K, per NIST’s cybersecurity framework.

Smart hybrid approaches ease migration:

• Phase 1: Deploy ZTNA for cloud apps (Office 365, Salesforce), keep VPN for on-prem legacy systems
• Phase 2: Implement ZTNA connectors for data center applications
• Phase 3: Retire VPNs after full app onboarding (typically 18-24 months)

Financial firms often maintain VPNs for mainframe access while routing web traffic through ZTNA. This cuts attack surface by 70% without replacing legacy investments. For budgeting, consider our interactive TCO calculator.

Vendor deep dive: Implementing ZTNA in Fortinet and Cisco environments

For Cisco-heavy enterprises, Cisco Zero Trust integrates with AnyConnect VPN clients, enabling gradual migration. Policy sets can enforce ZTNA for high-risk users while maintaining VPN for others. Performance tests show sub-25ms latency when accessing Azure-hosted apps.

Fortinet’s approach leverages FortiGate NGFW infrastructure:

1. Deploy FortiGate as ZTNA proxy (reusing existing hardware)
2. Shift from IP-based to application-centric policies in FortiOS
3. Enable FortiClient for endpoint posture checks

A healthcare provider secured patient records by applying ZTNA to their Epic EHR system via Fortinet, blocking ransomware attempts that previously bypassed VPNs. Both vendors support SAML integration, but Cisco requires ISE for full policy orchestration – a $50K+ investment that impacts ROI timelines.

Conclusion

Traditional VPNs increasingly struggle with modern threats and distributed workforces, while SSL/TLS VPN vs Zero Trust evaluations consistently favor ZTNA for security and scalability. By eliminating lateral movement risks through microsegmentation and improving performance via local breakout, Zero Trust delivers both enhanced protection and better user experiences. For most organizations, a phased hybrid approach – starting with cloud apps and high-value data – offers the smoothest transition. As you modernize access controls, prioritize solutions that integrate with existing investments like Cisco ISE or FortiGate. Ready to quantify benefits for your environment? Download our ZTNA readiness assessment toolkit to build your business case.