Tagged: VPN
7 posts · browse all tags
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Two Ways to Lose a VPN Gateway: FortiBleed's Credential Harvest and PAN-OS's Forged Auth Cookie
Two 2026 VPN gateway incidents, same attack surface, opposite root causes. FortiBleed has no CVE and no patch: a hashing migration that never finished, cracked at scale. CVE-2026-0257 is a real code defect: a certificate reused for two trust purposes that led straight to Qilin ransomware.
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One Crafted Request From a Reload: Inside CVE-2026-20349 on Cisco Secure Firewall ASA and FTD
An unauthenticated attacker who can reach the Remote Access SSL VPN service on an ASA or FTD device can crash it with one crafted HTTP request. No login, no workaround, just a reload. What CVE-2026-20349 actually is, and why VPN-facing edges keep being the softest part of the firewall.
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IPsec Deep Dive Part 1: ESP, AH, and How IKE Phase 1 Actually Brings a Tunnel Up
IPsec underpins every Fortinet SDWAN overlay this blog has built, and it's never had its own deep dive. Part 1 fixes that: the SA model, ESP vs AH, tunnel vs transport, and a message-by-message walk through IKEv1 main mode, aggressive mode, and IKEv2.
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IPsec Deep Dive Part 2: Phase 2, Child SAs, and the Anatomy of an ESP Packet
Phase 1 built a control channel and protected nothing. Part 2 covers the negotiation that actually moves data: quick mode and child SAs, traffic selectors, PFS, rekeying, and anti-replay — then dissects an ESP packet field by field, down to the MTU math.
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IPsec Deep Dive Part 3: NAT vs IPsec — NAT-T, Port Forwarding, and the Fortinet SDWAN Reality
NAT breaks IPsec three distinct ways — AH's ICV, ESP's missing ports, and IKE's rewritten source port. Part 3 covers each break, how NAT-D detects it and NAT-T's UDP 4500 encapsulation repairs it, when port forwarding is still required, and what it all means for SDWAN spokes behind CPE NAT.
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NSE4 Part 7: SSL VPN
Part 7 of the NSE4 study series — SSL VPN modes (web, tunnel, full), portals, realms, MFA, split tunnelling and the diagnostic commands for tracking down a stuck client.
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NSE4 Part 8: IPsec VPN
Part 8 of the NSE4 study series — IKEv1 vs IKEv2, route-based vs policy-based, site-to-site and dial-up, NAT traversal, dead peer detection, and the two diagnostic commands that separate a Phase 1 problem from a Phase 2 problem.