🌐The VPN Trap: Why Remote Access Is Today’s Hidden Vulnerability

VPNs are still a cornerstone of remote access and secure tunneling — but over the last 18 months they’ve become one of the most-targeted entry points for attackers. Vendors, appliances and client apps repeatedly show the same patterns: unauthenticated bugs, poor default configurations, leaked traffic, and messy post-exploitation toolkits that make a single flaw very costly. Below I’ll explain the common failure modes, summarize the most important recent attacks you need to know about, and give practical, prioritized recommendations you can act on today.

Quick TL;DR

• Recent high-risk VPN flaws have been actively exploited in the wild (zero-days and high-severity CVEs). Google Cloud+1

• Attackers are chaining VPN exploits with post-exploit tooling to steal configs and pivot. CISA

• Misconfigured or buggy client apps can leak IPv6 or bypass firewall rules, exposing real IPs. TechRadar

• Fixes: patch quickly, enforce MFA, segment VPN users, monitor telemetry, and remove exposed management interfaces.
  

How VPNs fail — common vulnerability patterns

1. Unauthenticated remote code execution / buffer overflows — a single unauthenticated flaw in the VPN gateway lets an attacker run code as SYSTEM/root. (Common in appliance CVEs.) Google Cloud

2. Authentication and session mishandling — credentials carried over during upgrades or migration, or weak default accounts, allow account takeover. The Hacker News

3. Configuration and protocol mistakes — IKEv2/SSL misconfig or legacy protocol support that exposes services to unauthenticated inputs. TechRadar

4. Client leaks and local firewall regressions — buggy client apps that leak IPv6 traffic or modify iptables and fail to restore them, exposing real IP address and defeating split-tunnel expectations. TechRadar

5. Post-exploit tooling and config theft — attackers reuse known exploits to create artifacts that persist on devices and extract configuration/keys for later use. CISA
   

Recent & current attacks you should know about (short & sharp)

• Ivanti Connect Secure / Pulse Secure — zero-day exploitation in the wildMultiple critical vulnerabilities affecting Ivanti Connect Secure appliances were publicly disclosed and seen exploited (unauthenticated stack buffer overflows and similar RCEs). Threat actors exploited them in late-2024 into 2025 to gain remote code execution without valid credentials. Patch or mitigate these immediately. Google Cloud+1

• SonicWall SSL VPN — active exploitation tied to ransomware (Akira)Attackers have re-leveraged a high-severity SonicWall SSL VPN flaw (CVE-2024-40766 and related issues) to mount intrusions that later led to ransomware activity in mid-2025. This is a reminder that disclosed but unpatched VPN flaws are attractive vectors for ransomware groups. The Hacker News

• Fortinet post-exploitation campaignsThreat actors are packaging post-exploitation techniques that reuse previously disclosed Fortinet FortiGate flaws to create files enabling read access and configuration theft — a clear pattern of chaining older vulnerabilities for continued access. CISA

• WatchGuard Firebox IKEv2 advisory (critical)WatchGuard published a critical advisory showing that the Firebox “iked” process could be abused in IKEv2 contexts—affecting both mobile and branch office VPNs — and issued patches plus temporary workarounds. Even if you removed dynamic peers, static configs left devices vulnerable. Patch or apply the vendor workaround. TechRadar

• Client-side app problems: PureVPN Linux leak (example of client bugs)A recent disclosure showed PureVPN’s Linux clients leaking IPv6 traffic and altering iptables upon connect/disconnect—highlighting that client apps can themselves be a reverse-door or privacy failure. If you rely on vendor client apps, test them and follow vendor guidance. TechRadar
  

Real-world impact

• Network takeover & lateral movement — RCE on a VPN gateway often equals immediate access to internal networks, user sessions, and sometimes credential stores.

• Data exfiltration & ransomware — VPN compromise is an effective way to reach high-value servers; ransomware actors repeatedly exploit VPN flaws as initial access. The Hacker News+1

• Persistent access using configs/secrets — stolen configs, tokens, or keys allow repeated re-entry even after the initial vulnerability is patched.
  

Actionable recommendations — prioritized (do these now)

Emergency (within hours)

1. Patch critical VPN appliances & clients now — if you run Ivanti, SonicWall, Fortinet, WatchGuard or other appliances, check vendor advisories and apply hotfixes/patches immediately. If you can’t patch, apply the vendor’s temporary mitigations. TechRadar+3Google Cloud+3Rapid7+3

2. Block exposed management endpoints — remove public access to admin panels and management interfaces (place behind jump hosts or allowlist).

3. Force password resets and rotate service credentials for accounts that may have been exposed or not reset after migrations/upgrades. The Hacker News

High priority (within 24–72 hours)

4. Require MFA for VPN access — stop relying on password-only authentication. Use strong device-based or hardware MFA for all remote access.

5. Segment VPN users and limit access scopes — use least privilege: remote users should not have blanket network access. Micro-segmentation reduces blast radius.

6. Disable unused VPN protocols and features — remove legacy protocols (PPTP/L2TP where present), and disable split-tunneling for sensitive user groups unless strictly necessary.
   

Detection & hardening

7. Enhance logging & telemetry — send VPN logs to SIEM/EDR, watch for abnormal successful logins, unusual post-login activity, or new config exports.

8. Hunt for IOCs and post-exploit artifacts — look for known artifacts tied to recent campaigns (config files, unknown binaries, scheduled tasks). CISA

9. Test client behavior — audit VPN clients for IPv6 leaks, DNS leaks, and whether clients alter firewall state in unexpected ways. If a vendor client behaves poorly, instruct users to avoid it until fixed. TechRadar

Longer-term posture

10. Shift to modern access models where appropriate — consider Zero Trust Network Access (ZTNA) for sensitive apps; ZTNA reduces reliance on network-level VPNs for app access.

11. Regular vulnerability scans and emergency patch playbook — maintain an up-to-date inventory of exposed VPN assets and run authenticated scans; build an emergency response playbook for VPN zero-days.
    

Detection recipes (practical SIEM/EDR rules)

• Alert on successful admin login outside business hours + source IP external to corporate ASN

• Alert on large configuration exports or unexpected file reads from /config, /var, or device backup endpoints

• Alert on unexpected firmware/OS reboots after an exploit disclosure window

• Watch for telemetry anomalies: high volumes of SMB/LDAP/SQL connections from an IP recently authenticated via VPN
  

Final words — treat VPNs like crown jewels

VPN gateways are high-value targets: a single unauthenticated flaw can give an attacker immediate runway into your estate. The current pattern is predictable: researchers (and attackers) find appliance or client bugs → vendors publish advisories → attackers scan and exploit unpatched systems. The fastest way to reduce risk is triage + remediation: patch, block, rotate, enforce MFA, lock down admin interfaces, and instrument detection.