🚨 FortiGate Devices Exploited to Breach Networks and Steal Service Account Credentials
Threat actors are actively targeting FortiGate Next-Generation Firewall appliances as entry points to breach victim networks, with recent campaigns singling out healthcare, government, and managed service providers. By exploiting known vulnerabilities or weak credentials, attackers extract configuration files containing service account credentials and network topology information. These compromised devices then become launchpads for deeper network infiltration, including Active Directory compromise and data exfiltration.
The campaign leverages known FortiGate flaws:
🔴 CVE-2025-59718
🔴 CVE-2025-59719
🔴 CVE-2026-24858
🔴 Attackers also exploit weak credentials and misconfigurations where devices are left exposed with default or easily guessable passwords.
Why FortiGate Devices?
FortiGate appliances have considerable access to the environments they protect. In many configurations, they connect to authentication infrastructure such as Active Directory (AD) and Lightweight Directory Access Protocol (LDAP). This setup allows the firewall to map roles to specific users and accelerate security responses, but it also creates a dangerous opportunity for attackers.
When threat actors break into FortiGate devices through vulnerabilities or misconfigurations, they gain access to:
→ Service account credentials stored in configuration files.
→ Network topology information.
→ Direct pathways into AD and LDAP environments.
🎯 The Attack Chain
🔴 Case 1: Initial Access Broker Establishes a Foothold
→ In November 2025, attackers breached a FortiGate appliance
→ Created a new local administrator account named "support"
→ Set up four new firewall policies allowing the account to traverse all zones without restrictions
→ Periodically checked device accessibility, consistent with an initial access broker (IAB) establishing a foothold for sale to other criminals
In February 2026, a new attacker likely:
→ Extracted the configuration file containing encrypted service account LDAP credentials
→ Decrypted the credentials and authenticated to AD using the fortidcagent service account in clear text
→ Enrolled rogue workstations in AD, gaining deeper access
→ Initiated network scanning, at which point the breach was detected and halted
🔴 Case 2: Rapid Deployment of Remote Access Tools
→ In late January 2026, attackers moved swiftly from firewall access to deploying remote access tools: Pulseway and MeshAgent
→ Downloading malware from an AWS cloud storage bucket via PowerShell
→ Launching Java malware through DLL side-loading
→ Exfiltrating NTDS.dit file and SYSTEM registry hive to external server 172.67.196[.]232 over port 443
⚠️ Targeted Sectors: Healthcare organizations, Government agencies, Managed service providers (MSPs).
Next-Generation Firewalls have become ubiquitous because they integrate security controls with management features like AD integration. But this same integration makes them high-value targets for:
→ State-aligned actors conducting espionage.
→ Financially motivated attackers pursuing ransomware.
→ Initial access brokers selling compromised footholds.
→ A compromised firewall is a gateway to the entire network, complete with service account credentials that unlock AD, LDAP, and beyond.