Top Highlights
- Cybercriminals are exploiting a patched vulnerability (CVE-2020-12812) in Fortinet FortiGate devices, bypassing two-factor authentication and gaining unauthorized VPN or admin access.
- The flaw arises from case sensitivity mismatches between FortiGate usernames and LDAP directories, allowing attackers to bypass 2FA by using case variations in login credentials.
- Exploitation requires local users with 2FA referencing LDAP groups, which can lead to privilege escalation or VPN access without tokens, signaling a critical compromise.
- To mitigate, organizations should update firmware to version 6.0.10+ or higher, disable username case sensitivity, remove unnecessary LDAP groups, and audit logs for suspicious login attempts.
The Core Issue
Cybercriminals are actively exploiting a vulnerability in Fortinet’s FortiGate firewalls, dating back to July 2020. This flaw, known as CVE-2020-12812, arises from a mismatch in how FortiGate handles usernames—case-sensitive by default—versus LDAP directories like Active Directory, which ignore case. Attackers target misconfigured systems where local users have two-factor authentication (2FA) enabled and are also members of LDAP groups linked to specific policies. By entering username variations with different cases, hackers bypass 2FA because FortiGate falls back to LDAP authentication, which does not require 2FA verification. This allows them to gain unauthorized VPN access or elevated privileges. The threat has persisted because many devices remain unpatched or misconfigured, despite fixes rolled out in recent versions of FortiOS. Fortinet’s security team reports these incidents, urging administrators to audit their configurations immediately. To mitigate this risk, organizations should upgrade their firmware, disable case sensitivity on usernames, and remove unnecessary LDAP groups from policies. If they fail to act swiftly, they risk serious consequences, including data breaches and ransomware attacks.
What’s at Stake?
The issue of hackers exploiting a three-year-old FortiGate vulnerability to bypass two-factor authentication (2FA) poses a serious threat to any business. If your firewall is targeted, cybercriminals can gain unauthorized access, bypassing security measures meant to protect sensitive data. Consequently, your business faces risks such as data breaches, financial loss, and damage to reputation. Moreover, without robust defenses, hackers could move laterally within your network, escalating their intrusion. Therefore, every business relying on FortiGate firewalls must remain vigilant, update systems promptly, and strengthen their security protocols to prevent such exploits from causing harm.
Possible Next Steps
Quick action is crucial to limit damage, prevent further exploitation, and restore system integrity when vulnerabilities such as the three-year-old FortiGate flaw that enables hackers to bypass two-factor authentication are discovered.
Assessment
Conduct a comprehensive security assessment to identify whether the vulnerability has been exploited and evaluate the current security posture.
Patch Deployment
Apply the latest firmware updates and security patches released by Fortinet to close the known vulnerability.
Configuration Review
Review firewall and two-factor authentication configurations to ensure they are correctly set and not susceptible to bypass techniques.
Access Control
Implement strict access controls, reducing permissions to the minimum necessary and disabling any unneeded remote access methods.
Monitoring & Detection
Enhance monitoring on logs, especially login attempts and firewall activity, to detect signs of exploitation or ongoing attack.
User Training
Update staff on security best practices and the importance of recognizing suspicious activity related to breach attempts.
Incident Response
Activate incident response plans to contain and remediate breaches swiftly, including isolating affected systems and conducting forensic analysis.
Communication
Notify relevant stakeholders and, if required, regulatory bodies about the vulnerability and the steps taken to mitigate the risk.
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Disclaimer: The information provided may not always be accurate or up to date. Please do your own research, as the cybersecurity landscape evolves rapidly. Intended for secondary references purposes only.
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