VPNs Are an Attacker's Front Door. Close It with Zero Trust.

A fresh wave of automated login attempts against exposed VPN portals is the latest reminder of a hard truth: VPNs are an enterprise’s most visible, most targeted front door. When attackers can aim limitless credential stuffing, password spraying, and session hijacking at a single internet-facing portal, compromise becomes a numbers game: not a matter of if it happens, but when.

In the most recent series of events, threat actors are launching large waves of login attempts against publicly exposed VPN portals such as GlobalProtect. These campaigns use commodity botnets, leaked credential dumps, proxy networks, and MFA fatigue tactics to cycle through accounts until they gain unauthorized access. Once adversaries establish a foothold, they exploit the perceived trust of the VPN connection to move laterally, escalate privileges, and blend in as legitimate users.

Attackers love VPNs. VPNs pose serious security risks because their gateways are publicly exposed, making them constant, easy-to-find targets for scanning, brute-forcing, and fingerprinting. A single successful login often grants overly broad access to the internal network and numerous applications, which may exceed the user's need.

Compounding this problem, attackers can easily exploit weak authentication and reused credentials to gain access through "spray-and-pray" attacks. Patching VPN appliances is often a complex, risky, and slow process. The implicit trust model of traditional networks aids attackers, by making lateral movement easier.

If you still run VPNs today, you should immediately lock down the portal with strong security, limit the blast radius with least-privileged access, and set up solid monitoring and incident response in case something happens.

The problem isn’t just weak controls around VPNs: it’s the VPN model itself. Any solution that exposes a network entry point to the internet invites exactly the sort of automated abuse we’re seeing. Zero trust network access (ZTNA) changes the game.

• No inbound access, no exposed portals: Zscaler Private Access (ZPA) connects users to apps through brokered, outbound-only connections. Applications are hidden behind the Zscaler Zero Trust Exchange—no public IPs, open ports, or VPN concentrators to scan or brute-force.
• App-level access, not network access: Users get least-privileged access to specific apps based on identity, context, and policy. There’s no “flat” network to roam, significantly reducing lateral movement.
• Autonomous user-to-app segmentation: Powered by AI, ZPA eliminates the manual burden of defining micro-perimeters and ensures least-privileged access is dynamically enforced, a capability fundamentally missing from traditional network-centric VPNs.
• Continuous, risk-based trust: Access decisions adapt in real time using identity, device posture, user behavior, and location. If risk spikes, access can step-up MFA, restrict, or cut off sessions automatically.
• Phishing-resistant authentication: ZPA integrates with modern IdPs and FIDO2 to eliminate passwords for high-value workflows and stop MFA fatigue tactics.
• Strong posture and segmentation everywhere: Device checks, microtunnels per app, and double-encrypted connections protect traffic on any network without hairpinning or split-tunnel tradeoffs.
• Operational simplicity: Our cloud-delivered service removes patching burden from fragile appliances and scales elastically under surges—legitimate or hostile.

1. Assess and prioritize: Inventory VPN use cases, app dependencies, and user groups; pick high-risk or easy-to-isolate apps to start.
2. Connect apps safely: Deploy ZPA App Connectors beside each app (data center/cloud) with outbound-only connections—no public IPs or inbound firewall changes.
3. Integrate identity and posture: Hook up your IdP (SAML/OIDC) and device posture sources (EDR/MDM); define least-privilege, app-specific policies.
4. Publish and pilot: Publish initial app segments, enable Zscaler Client Connector, and pilot with contained groups (admins/contractors); tune policies and MFA.
5. Scale and retire VPN: Expand in waves, tighten remaining VPN access during transition, cut over cleanly, monitor/optimize, then decommission concentrators and close inbound ports.

VPNs are a liability: a conspicuous front door that adversaries will keep kicking until it opens. You can harden and monitor that door, but the safest, most sustainable answer is to remove it altogether. Zero trust with Zscaler replaces guesswork and implicit trust with app-specific, risk-aware access that attackers can’t easily see, spray, or brute-force.

Interested in learning more? Schedule a meeting with our product experts today.