AI Detection for Fortinet Flaw Exploitation—Fast

A CVSS 9.1 vulnerability doesn’t stay “theoretical” for long anymore. This week’s Fortinet incident proved it again: within days of public disclosure, real attackers were already abusing authentication bypass flaws to break into Internet-exposed devices, target admin accounts, and export configurations that include hashed credentials and network details.

Most companies get one part right: they rush to patch. Where they still get burned is everything around patching—the hours or days between disclosure, maintenance windows, and full rollout, plus the quiet reality that perimeter appliances often have management interfaces exposed longer than anyone wants to admit. That gap is exactly where AI-powered threat detection earns its keep.

This post breaks down what’s happening with the Fortinet flaws, why these attacks are so effective, and the practical ways security teams can use AI in cybersecurity to spot exploitation early, contain it fast, and reduce blast radius—even if you can’t patch today.

What’s happening with the Fortinet vulnerabilities (and why it’s urgent)

The core issue is straightforward: two critical authentication bypass vulnerabilities (CVE-2025-59718 and CVE-2025-59719, both CVSS 9.1) affect several Fortinet products, including FortiOS, FortiWeb, FortiProxy, and FortiSwitchManager.

The key detail: exploitation involves specially crafted SAML messages that can bypass SSO login checks when FortiCloud SSO is enabled. Once attackers can impersonate an authenticated user—especially an admin—they can do what perimeter-device attackers always do: turn a network control point into a network control plane.

CISA added CVE-2025-59718 to its Known Exploited Vulnerabilities catalog based on evidence of active exploitation. That matters operationally even if you’re not a federal agency because it’s a signal: this isn’t “scan noise.” It’s a working playbook.

The overlooked risk: “enabled by default” vs. “enabled by workflow”

FortiCloud SSO may be disabled in factory settings, but it can become enabled through normal admin workflows—such as registering devices via GUI using FortiCare—unless an admin explicitly disables an “Allow administrative login” toggle.

I’ve seen this pattern repeatedly: security teams assume a feature is off because “we didn’t turn it on.” But product onboarding steps effectively turn it on. Attackers bet on that ambiguity. They usually win.

How attackers turn an auth bypass into a future breach

Once attackers bypass authentication, the best move isn’t always ransomware or immediate destruction. Often it’s quiet positioning.

In the observed activity, attackers:

• Focused on admin accounts
• Used the access to export device configurations
• Exfiltrated data (including hashed credentials and sensitive configuration context)

That exported config is valuable because it can include:

• VPN settings and user/group mappings
• Network topology and routing choices
• Firewall policy structure (what’s allowed where)
• Admin account details and credential artifacts

A stolen firewall configuration is a blueprint for follow-on attacks, not just a souvenir.

Why hashed credentials still matter

Teams sometimes underestimate “only hashed” credentials. Attackers don’t need to crack everything—just something useful. Offline cracking is practical when passwords are weak or reused. Even one cracked admin credential can become:

• A persistent access method on the device
• A stepping stone into VPN, directory services, or other management planes
• A way to create new rogue accounts that survive patching

This is also why the right response isn’t just patching. It’s patch + validate + rotate credentials + hunt for persistence.

Where AI threat detection fits (and why rule-only monitoring falls behind)

AI in cybersecurity is most valuable in incidents like this because the early signals are rarely clean, consistent, or conveniently mapped to a single signature.

Here’s the direct answer: AI-powered detection helps you find exploitation while it’s still a handful of anomalous events, not a full-blown incident.

What AI can detect during Fortinet auth bypass exploitation

Even when the attacker “logs in” after bypassing auth checks, the session behavior tends to look wrong. AI models that learn baselines across identity, network, and device telemetry can flag:

• Unusual admin login patterns: odd geolocation, hosting provider IP space, new ASN, impossible travel, or logins at abnormal times
• SSO anomalies: spikes in SAML auth attempts, malformed message structures, or unusual token lifetimes
• Management-plane behavior changes: sudden config exports, backup downloads, or settings enumeration
• Session artifacts: abnormal jsconsole sessions, unfamiliar user agents, or short “burst” admin sessions
• Post-auth lateral movement signals: new SSL VPN tunnel creation, unexpected policy edits, or routing changes

The practical difference versus static rules: rules catch what you already know to look for. AI catches combinations—for example, “new admin session + new IP reputation + config export within 90 seconds.”

Why this matters right now (December timing is not neutral)

Late December is peak risk for two reasons:

1. Change freezes and thin staffing slow patching and investigation.
2. Attackers know it—and they plan campaigns around it.

AI-supported security operations helps close that holiday gap by triaging the highest-risk anomalies first and reducing the time humans spend staring at low-signal alerts.

A practical response plan: patch, contain, then verify with AI-assisted hunting

If you run Fortinet gear, you want a plan that works whether you can patch in 2 hours or 2 weeks.

Step 1: Reduce exposure immediately (today)

If the management interface is Internet-facing, treat that as an emergency. Immediate containment actions:

• Restrict admin access to trusted IP ranges only (jump host, VPN, or allowlist)
• Disable admin access over http/https on untrusted interfaces
• Disable FortiCloud SSO administrative login temporarily if you can’t patch
• Confirm you have out-of-band access for recovery (console/HA)

This is where I’m opinionated: if your firewall admin UI is exposed to the open Internet without strict controls, you’re not “behind.” You’re already in the incident timeline, just earlier than the breach.

Step 2: Patch with precision (this week)

Fortinet has released fixes across product lines. For FortiOS, patched versions include 7.6.4, 7.4.9, 7.2.12, 7.0.18 or higher (per vendor guidance). Some older lines are unaffected.

Two practical patching tips that reduce failures:

1. Inventory by exact version and feature state (is FortiCloud SSO enabled?)—not just “we’re on Fortinet.”
2. Patch the most exposed devices first: Internet-facing edge appliances, then internal management nodes.

Step 3: Assume compromise when signals match (and prove otherwise)

If you see suspicious SSO logins or admin anomalies, act as if credentials and configuration data are already in attacker hands.

Do these in parallel:

• Reset and rotate all device admin credentials (and any accounts referenced in configs)
• Review for new or modified admin accounts
• Audit firewall policy and NAT rules for subtle backdoors
• Review SSL VPN config for new portals, users, or tunnels
• Export and compare configuration diffs against last known good

Step 4: Use AI-assisted hunting to validate “clean” after patching

Patching closes the known hole. It doesn’t remove whatever the attacker did after walking in.

An AI-driven hunt should focus on a timeline:

1. Pre-disclosure to present: identify first anomalous SSO events
2. First anomalous SSO to config export: confirm if data left the device
3. Post-export: check for persistence (accounts, policy edits, VPN tunnels)

If your SOC stack supports it, prioritize detections that correlate:

• Identity events + firewall admin logs
• Egress traffic patterns from management plane
• Configuration-change telemetry

The verification question isn’t “Did we patch?” It’s “Did anyone touch the box before we patched—and what did they leave behind?”

How to operationalize AI for perimeter-device attacks (without boiling the ocean)

Security leaders often like AI in theory and struggle with it in execution. Here’s what works in real environments.

Build three “fast paths” for AI in cybersecurity operations

You don’t need 50 models. You need 3 high-signal outcomes:

1. Anomaly detection for privileged access

   • Baseline normal admin behavior
   • Alert on first-time sources, hosting provider IPs, unusual auth methods

2. Automated correlation for management-plane actions

   • Login → config export → policy edit → VPN change
   • Raise severity when actions happen in short sequence

3. AI-assisted triage and response recommendations

   • Provide an analyst with: suspected timeline, impacted devices, likely persistence checks
   • Pre-fill containment actions (disable SSO, restrict admin interface, rotate creds)

A simple detection playbook you can implement quickly

If you’re tuning detections for this Fortinet-style campaign, start with:

• Alert when FortiCloud SSO admin login occurs from a never-seen IP/ASN
• Alert when configuration export/backup download happens within 5 minutes of a new admin session
• Alert on new admin account creation or privilege changes
• Alert on unexpected SSL VPN authentication patterns following admin activity

Then let AI help reduce noise by ranking incidents where multiple signals co-occur.

What to do next if you want fewer fire drills in 2026

Fortinet won’t be the last perimeter platform hit with an auth bypass. The pattern is stable:

• A feature that’s “optional” becomes “accidentally enabled”
• Attackers automate scanning and exploitation within days
• Defenders race patch windows while attackers race exposure windows

The teams that consistently avoid breach headlines do two things well: they minimize management-plane exposure, and they use AI threat detection to spot abnormal behavior early enough that containment is boring.

If you’re responsible for Fortinet devices (or any edge security stack), treat this incident as a stress test. Do you know which devices have FortiCloud SSO enabled? Are admin interfaces restricted? Can your SOC detect “auth bypass-like” behavior even when credentials appear valid?

That last question is the one that decides whether the next critical vulnerability becomes a patch ticket—or an incident.