CVE-2023-26208 in FortiAuthenticator
Summary
by MITRE • 03/09/2023
A improper restriction of excessive authentication attempts vulnerability [CWE-307] in Fortinet FortiAuthenticator 6.4.x and before allows a remote unauthenticated attacker to partially exhaust CPU and memory via sending numerous HTTP requests to the login form.
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Analysis
by VulDB Data Team • 03/09/2023
The vulnerability identified as CVE-2023-26208 represents a critical weakness in Fortinet FortiAuthenticator versions 6.4.x and earlier, classified under CWE-307 which specifically addresses improper restriction of excessive authentication attempts. This flaw enables remote attackers to exploit the authentication mechanism without prior authentication credentials, creating a significant security risk for organizations relying on this identity and access management solution. The vulnerability stems from insufficient rate limiting and authentication attempt controls within the web interface, particularly affecting the login form functionality that serves as the primary entry point for user authentication processes.
The technical exploitation of this vulnerability involves sending a high volume of HTTP requests to the authentication endpoint, specifically targeting the login form accessible to unauthenticated users. This attack pattern leverages the absence of proper throttling mechanisms that would normally limit the number of authentication attempts within a given time frame. The attacker can systematically overwhelm the system resources by continuously submitting login requests, causing the FortiAuthenticator to consume excessive CPU cycles and memory resources. This resource exhaustion occurs because the system lacks effective mechanisms to detect and mitigate repetitive authentication attempts from the same source, allowing malicious actors to deplete system capacity without successful authentication.
The operational impact of CVE-2023-26208 extends beyond simple resource consumption, potentially leading to service disruption and denial of legitimate authentication services for authorized users. When the system becomes overwhelmed with excessive authentication requests, it may experience degraded performance or complete service unavailability, affecting the organization's ability to manage user access and authentication. This vulnerability directly impacts the availability aspect of the CIA triad, as it can render the authentication service ineffective for legitimate users who require access to protected systems. The attack can be executed remotely without requiring any prior authentication credentials, making it particularly dangerous as it can be launched from any network location without detection.
Organizations utilizing FortiAuthenticator versions affected by this vulnerability should implement immediate mitigations to protect their authentication infrastructure. The primary recommendation involves applying the latest security patches provided by Fortinet to address the root cause of the improper authentication attempt restriction. Additionally, network-level controls such as rate limiting at the firewall or reverse proxy level can provide effective protection by limiting the number of requests from individual IP addresses within specific time intervals. Implementing intrusion prevention systems with signature-based detection capabilities can help identify and block malicious authentication attempt patterns. The mitigation strategy should also include monitoring and logging of authentication attempts to detect unusual patterns that may indicate exploitation attempts, aligning with security best practices outlined in the NIST Cybersecurity Framework and MITRE ATT&CK framework under the credential access and privilege escalation domains.