In the rapidly shifting landscape of cybersecurity, vigilance is paramount. Yet, an alarming truth has recently resurfaced: over 10,000 Fortinet firewalls globally remain susceptible to a multi-factor authentication (MFA) bypass vulnerability that was publicly disclosed more than five and a half years ago. This persistent exposure, highlighted by Shadowserver and confirmed by Fortinet, underscores a critical gap in security posture for numerous organizations. As a cybersecurity analyst, the implications of such a long-standing vulnerability are deeply concerning, particularly given the active exploitation confirmed by Fortinet – an active threat that continues to loom large.

The Persistent Threat of CVE-2020-12812

The vulnerability in question, tracked as CVE-2020-12812, stems from an improper authentication flaw within FortiOS SSL VPN. Unlike many vulnerabilities that are quickly patched and forgotten, this particular issue has demonstrated remarkable staying power. Its longevity in the wild, coupled with the sheer number of affected devices, makes it a prime target for threat actors.

Specifically, the source information details that over 10,000 Fortinet firewalls continue to be exposed. This isn’t just a theoretical risk; Fortinet confirmed active exploitation of this flaw as late as 2025. This means attackers are actively leveraging this weakness, bypassing crucial MFA protections that are often considered a cornerstone of modern security.

Understanding the MFA Bypass Mechanism

Multi-factor authentication is designed to add an extra layer of security beyond just a password. By requiring two or more forms of verification, MFA significantly reduces the risk of unauthorized access even if credentials are stolen. However, the improper authentication in FortiOS SSL VPN that constitutes CVE-2020-12812 undermines this critical defense. While the precise technical details of the bypass mechanism are complex, the core issue allows an attacker to circumvent the MFA challenge, gaining unauthorized access to the network resources protected by the firewall.

Such a bypass is particularly dangerous for VPNs. VPNs are often the gateway to an organization’s internal network, making them high-value targets. A successful bypass could lead to lateral movement within the network, data exfiltration, or even the deployment of ransomware or other malicious payloads.

Why the Delay? Challenges in Patching and Awareness

The existence of over 10,000 active vulnerabilities five and a half years after disclosure raises significant questions about patch management and security awareness. Several factors could contribute to this alarming statistic:

• Lack of Awareness: Despite public disclosure and the addition to reports like Shadowserver’s Vulnerable HTTP Report, many organizations may simply be unaware of their exposure.
• Under-Resourced IT Teams: Smaller organizations or those with limited IT budgets may struggle to keep up with the constant stream of patches and updates required for their infrastructure.
• Complexity of Updates: Updating network infrastructure, especially critical components like firewalls, can be complex and disruptive, leading to delays in implementation.
• Reliance on Outdated Systems: Some organizations may be running older versions of FortiOS that are no longer officially supported, making patching impossible without costly upgrades.
• Misconfigured Devices: Even if patches are applied, misconfigurations can inadvertently re-introduce vulnerabilities or leave gaps in protection.

Remediation Actions for CVE-2020-12812

For organizations currently utilizing Fortinet firewalls, immediate action is not just recommended, it’s imperative. Addressing CVE-2020-12812 requires a systematic approach:

• Patch Immediately: The most crucial step is to apply the latest security patches available from Fortinet for FortiOS SSL VPN. Ensure your FortiGate devices are running a patched version that addresses this vulnerability. Refer to official Fortinet advisories for specific version requirements.
• Conduct Vulnerability Scans: Utilize vulnerability assessment tools to scan your external perimeter and internal network for any instances of CVE-2020-12812. This helps confirm whether your devices are indeed vulnerable.
• Review VPN Configurations: Scrutinize your SSL VPN configurations to ensure they adhere to best practices. Disable unnecessary services and limit access to only essential personnel.
• Enforce and Monitor MFA: While this vulnerability bypasses MFA, it is critical to ensure MFA is universally enforced wherever possible across all access points. Even with patched systems, a layered security approach is always best. Implement strong monitoring for MFA failures or unusual login patterns.
• Network Segmentation: Implement network segmentation to limit the potential blast radius of a successful breach. If an attacker gains access through the VPN, segmentation can prevent them from easily moving to critical internal systems.
• Employee Training: Educate users about phishing attempts and social engineering tactics that might aim to circumvent security measures, even those in a multi-factor environment.

Tools for Detection and Mitigation

Leveraging the right tools is essential for identifying and addressing vulnerabilities like CVE-2020-12812. Here are some relevant tools:

Tool Name	Purpose	Link
FortiGate Firmware Download Portal	Official source for FortiOS firmware updates and patches.	https://support.fortinet.com/Download/FirmwareImages.aspx
Nessus	Vulnerability scanner capable of detecting a wide range of vulnerabilities, including those affecting Fortinet devices.	https://www.tenable.com/products/nessus
OpenVAS	Open-source vulnerability scanner that can be used for identifying network security weaknesses.	http://www.openvas.org/
Shadowserver Foundation Reports	Provides daily reports on vulnerable systems, including those exposed to CVE-2020-12812.	https://www.shadowserver.org/what-we-do/network-reports/vulnerable-http-report/

Final Thoughts on Proactive Security

The continued exposure of thousands of Fortinet firewalls to CVE-2020-12812 serves as a stark reminder that cybersecurity is an ongoing process, not a one-time fix. Proactive patch management, continuous vulnerability scanning, and robust security awareness training are indispensable. Organizations must prioritize the swift remediation of known vulnerabilities, especially those with confirmed active exploitation. Ignoring such critical flaws not only puts sensitive data at risk but also damages an organization’s reputation and can lead to significant financial and operational disruptions. Stay informed, stay vigilant, and secure your digital perimeter.