Listen to this Post
Introduction:
The perimeter is dead—and the FortiBleed campaign just buried it six feet deeper. SOCRadar researchers uncovered an active, automated credential theft operation targeting Fortinet firewalls and VPN gateways, compromising over 30,000 verified devices across 194 countries. What began as large-scale credential stuffing evolved into a self-sustaining harvesting network: compromised devices became sniffers, capturing credentials from passing traffic and feeding them back into the attack loop. This isn’t a theoretical supply chain risk—it’s an active, ongoing operation with millions of credentials potentially exposed across more than 100,000 organizations.
Learning Objectives:
- Understand the technical mechanics of the FortiBleed campaign, including automated scanning, credential stuffing, and post-compromise sniffing
- Master practical mitigation techniques for Fortinet devices, including CLI hardening, access controls, and detection strategies
- Learn to identify Indicators of Compromise (IoCs) and implement incident response procedures for compromised network appliances
- Understanding the Attack Chain: From Scanner to Sniffer
The FortiBleed operation is a masterclass in automated credential harvesting. The attackers scan the internet for Fortinet devices, then apply a curated password list—not random guesses, but credentials leaked from Fortinet devices in previous breaches. Each successful login is recorded and verified. But the attack doesn’t stop at initial access.
Once a device is compromised, the attackers deploy network sniffers that monitor all traffic passing through the firewall. Any credentials flowing across the network—whether plaintext or weakly encrypted—are captured and fed back into the scanning system. This creates a self-reinforcing loop: more compromises lead to more sniffing, which yields more credentials for further compromises. The database includes over 30,791 compromised access points across 194 countries, with telecommunications (5,616 entries) and government entities (591 entries across 111 domains) among the hardest-hit sectors.
What This Means for Defenders: Any organization with a Fortinet device appearing in this dataset should treat its network perimeter as already compromised. The attackers aren’t guessing—they’re using verified, working credentials.
- FortiGate CLI Hardening: Lock Down SSL-VPN Against Credential Stuffing
The most critical defense against credential stuffing is limiting login attempts and enforcing strong authentication. FortiGate administrators can implement the following CLI configurations immediately:
Step 1: Limit Login Attempts and Set Block Duration
config vpn ssl settings set login-attempt-limit 3 set login-block-time 300 end
This restricts users to three failed login attempts before a five-minute block. For high-security environments, reduce the limit to two attempts.
Step 2: Enforce Client Certificate Authentication
config vpn ssl settings set client-certificate enable end
Requiring client certificates makes stolen passwords useless on their own. The SSL-VPN connection won’t even proceed to the password prompt without a valid certificate.
Step 3: Block Known Malicious IP Ranges
config firewall address edit "Malicious_IPs" set subnet 0.0.0.0 0.0.0.0 set type geography set country "RU" "CN" "KP" "IR" next end config firewall policy edit 0 set srcintf "wan1" set dstintf "ssl.root" set srcaddr "Malicious_IPs" set action deny next end
Geo-blocking can eliminate massive volumes of automated attack traffic before it reaches the login portal.
Step 4: Hide the FortiGate Login Page
config system settings set gui-allow-unauth false end
Use local-in-policies to restrict administrative access to trusted IP ranges only.
- Detecting Compromised Devices: Sniffer Activity and Network Anomalies
Attackers deploying sniffers on compromised Fortinet devices leave traces. Network administrators should monitor for:
Indicators of Compromise (IoCs):
- Unexpected packet capture or sniffer processes running on the firewall
- Unusual outbound connections to command-and-control (C2) infrastructure
- Configuration file exfiltration attempts—attackers often extract encrypted LDAP credentials from configs
- SSL-VPN login attempts from anomalous geographic locations or at unusual hours
Detection Commands:
Check for active sniffer processes diagnose sniffer packet any "host <suspicious_IP>" 4 Review SSL-VPN login failures diagnose vpn ssl debug Examine system logs for unauthorized configuration changes execute log filter category 1 execute log display Check for unexpected administrative sessions diagnose sys session list | grep admin
Windows-Based Network Monitoring:
For organizations using FortiClient EMS, monitor for unauthorized endpoint management activity. CVE-2026-35616 allows unauthenticated attackers to bypass API authentication in FortiClient EMS versions 7.4.5 and 7.4.6, enabling credential stealers to be pushed to managed endpoints.
- Incident Response: What to Do If You’re in the Dataset
If your organization appears in the FortiBleed dataset—or if you suspect compromise—take these steps immediately:
Step 1: Assume Compromise
Treat the device as fully compromised. Do not simply change the password; the attacker may have deployed persistent backdoors or sniffers.
Step 2: Isolate and Investigate
- Disconnect the affected device from the network
- Capture forensic images of the system and logs
- Preserve evidence for legal and regulatory reporting
Step 3: Rotate All Credentials
- Change all local admin passwords on the FortiGate device
- Rotate service account credentials (LDAP, RADIUS, SSO) that may have been exposed
- Force password changes for all VPN users
Step 4: Upgrade Firmware
Ensure the device is running the latest FortiOS release. Many attacks exploit known vulnerabilities, including CVE-2026-24858 (SAML authentication bypass, CVSS 9.8) and CVE-2026-35616.
Step 5: Implement MFA Immediately
Deploy phishing-resistant MFA such as FIDO2 or certificate-based authentication. This renders stolen credentials ineffective even if attackers possess valid usernames and passwords.
5. Long-Term Hardening: Beyond the Firewall
The FortiBleed campaign exposes a fundamental architectural failure: relying on edge appliances with public-facing management interfaces in 2026 is no longer tenable.
Zero Trust Network Access (ZTNA):
Replace or supplement SSL-VPN with ZTNA solutions that authenticate users and devices continuously, rather than relying on a single perimeter gateway.
Network Segmentation:
Ensure that compromised edge devices cannot provide unrestricted access to internal networks. Implement micro-segmentation to limit lateral movement.
Continuous Monitoring:
Deploy Network Detection and Response (NDR) solutions that monitor traffic metadata for signs of attacker activity, including lateral movement, command and control, and data exfiltration.
Regular Password Audits:
The FortiBleed attackers relied on credentials leaked from previous breaches. Implement automated password rotation and enforce unique passwords across all administrative accounts.
What Undercode Say:
- The perimeter illusion is shattered. FortiBleed demonstrates that edge devices are not fortresses—they are attack surfaces. Organizations that treat firewalls as “set and forget” appliances are gambling with their entire network.
-
Automation changes the threat calculus. The self-feeding nature of this campaign—scan, compromise, sniff, harvest, repeat—means that a single weak credential can trigger a cascading compromise across thousands of devices. Defenders must match this automation with AI-driven threat intelligence and real-time response capabilities.
The attackers’ operational mistake—leaving their server exposed with a trove of operational files—allowed SOCRadar to uncover the campaign. But this stroke of luck shouldn’t be mistaken for strategy. The next campaign may not make the same error. Organizations must assume that similar operations are running undetected right now, targeting every vendor, every device, every perimeter. The question isn’t whether you’ll be targeted—it’s whether you’ll detect it before the attackers achieve their objectives. With over 30,000 devices already compromised and the operation still active, the window for proactive defense is closing fast.
Prediction:
- -1 Escalation of automated credential harvesting. The FortiBleed playbook—scan, stuff, sniff, feed—will be replicated against other network device vendors (Cisco, Palo Alto, SonicWall) within 12–18 months. The barriers to entry are low, and the rewards are immense.
-
-1 Ransomware gangs will acquire FortiBleed datasets. Initial Access Brokers (IABs) are already selling access to compromised Fortinet devices. As these datasets circulate underground, ransomware operators will leverage them for direct network infiltration, bypassing traditional phishing vectors.
-
-1 Regulatory backlash and liability waves. With over 100,000 organizations potentially exposed and credentials spanning 194 countries, class-action lawsuits and regulatory fines are inevitable. Organizations that failed to implement basic hardening—MFA, login limits, firmware updates—will face severe consequences.
-
+1 Accelerated adoption of passwordless authentication. The FortiBleed campaign provides the strongest business case yet for eliminating passwords entirely. Organizations will accelerate deployments of FIDO2, certificate-based authentication, and biometric MFA, rendering credential stuffing campaigns obsolete—at least for those who adopt.
-
+1 Growth of automated threat intelligence sharing. SOCRadar’s proactive notification to affected organizations and national CERTssets a precedent for private-sector threat intelligence sharing. This model will expand, with more vendors disclosing active campaigns before they reach critical mass.
▶️ Related Video (84% Match):
https://www.youtube.com/watch?v=BZQ0wFoQDmc
🎯Let’s Practice For Free:
🎓 Live Courses & Certifications:
Join Undercode Academy for Verified Certifications
🚀 Request a Custom Project:
Secure, high-velocity infrastructure and disruptive technological engineering. Contact our engineering team for high-tier development and proprietary systems:
[email protected]
💎 Smart Architecture | 🛡️ Secure by Design | ⭐ Trusted by Thousands
IT/Security Reporter URL:
Reported By: Huzeyfe We – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
