CVE-2018-13374 in FortiOS
Summary
by MITRE
A Improper Access Control in Fortinet FortiOS allows attacker to obtain the LDAP server login credentials configured in FortiGate via pointing a LDAP server connectivity test request to a rogue LDAP server instead of the configured one.
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Analysis
by VulDB Data Team • 09/09/2024
This vulnerability resides in Fortinet FortiOS software where improper access control mechanisms fail to validate the legitimacy of LDAP server connections. The flaw specifically affects FortiGate devices that utilize LDAP authentication for user access control, creating a significant security risk when administrators configure LDAP server connectivity. The vulnerability stems from the software's inability to properly authenticate or verify the identity of LDAP servers during connectivity testing phases, allowing malicious actors to intercept and extract sensitive authentication credentials.
The technical implementation of this vulnerability occurs during the LDAP server connectivity testing process where FortiOS sends authentication requests to verify server connectivity. When an attacker sets up a rogue LDAP server and tricks the FortiGate device into connecting to it, the system inadvertently transmits the configured LDAP server credentials to the attacker-controlled server. This represents a classic case of insecure credential handling and inadequate server validation mechanisms. The flaw operates at the application layer and can be exploited through network-based attacks that manipulate the LDAP connection flow.
The operational impact of this vulnerability extends beyond simple credential theft, as it provides attackers with persistent access to LDAP authentication systems that may control access to critical network resources. Once credentials are obtained, attackers can perform lateral movement within the network, escalate privileges, and potentially gain access to additional systems that rely on the same LDAP infrastructure. The vulnerability affects multiple FortiOS versions and impacts organizations that depend on LDAP authentication for their network security policies, creating a substantial risk for enterprises with complex network architectures.
Organizations should implement immediate mitigations including network segmentation to prevent unauthorized access to LDAP servers, disabling unnecessary LDAP connectivity testing features, and implementing strict firewall rules to control LDAP traffic flows. The vulnerability aligns with CWE-284 access control flaws and maps to ATT&CK technique T1078 legitimate credentials for maintaining access. Additional protective measures include regular credential rotation, monitoring for unusual LDAP connection patterns, and implementing network intrusion detection systems to identify potential rogue server activities. Security teams must also review and validate all LDAP server configurations to ensure proper authentication mechanisms are in place.
The vulnerability demonstrates the critical importance of proper input validation and server authentication in security-critical applications, particularly those handling authentication credentials. Organizations should conduct comprehensive security assessments of their FortiOS deployments and ensure all devices are updated with the latest security patches from Fortinet. Regular security audits should focus on authentication mechanisms and access control configurations to prevent similar issues from occurring in other network components. The incident highlights the need for robust credential management practices and the implementation of zero-trust network principles to minimize the impact of such vulnerabilities.