CVE-2023-22641 in FortiOS
Summary
by MITRE • 04/11/2023
A url redirection to untrusted site ('open redirect') in Fortinet FortiOS version 7.2.0 through 7.2.3, FortiOS version 7.0.0 through 7.0.9, FortiOS versions 6.4.0 through 6.4.12, FortiOS all versions 6.2, FortiOS all versions 6.0, FortiProxy version 7.2.0 through 7.2.2, FortiProxy version 7.0.0 through 7.0.8, FortiProxy all versions 2.0, FortiProxy all versions 1.2, FortiProxy all versions 1.1, FortiProxy all versions 1.0 allows an authenticated attacker to execute unauthorized code or commands via specially crafted requests.
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Analysis
by VulDB Data Team • 04/28/2023
The vulnerability identified as CVE-2023-22641 represents a critical open redirect flaw within Fortinet's FortiOS and FortiProxy software ecosystems. This security weakness manifests as an improper validation of user-supplied input during URL redirection processes, allowing malicious actors to manipulate the redirection flow to point to arbitrary external domains. The vulnerability affects multiple major versions across both FortiOS and FortiProxy products, spanning from version 6.0 through 7.2, creating a substantial attack surface that impacts organizations relying on these network security solutions. The flaw specifically resides in the authentication handling mechanisms where the system fails to properly validate or sanitize redirection URLs, enabling attackers to craft malicious requests that bypass normal security controls.
From a technical perspective, this vulnerability operates as an authenticated open redirect vulnerability classified under CWE-601, where the system accepts user-controllable input that determines the destination of a redirect operation without adequate validation. The flaw enables attackers to construct specially crafted HTTP requests that contain malicious redirect URLs, which when processed by the vulnerable Fortinet appliances, will redirect users to attacker-controlled domains. This behavior creates a dangerous chain of potential attacks including phishing campaigns, credential theft, and malware distribution, as users may be unknowingly redirected to malicious sites that appear to originate from trusted Fortinet appliances. The authentication requirement for exploitation means that attackers must first obtain valid credentials, but once achieved, the impact can be severe as the vulnerability allows for arbitrary code execution through the manipulated redirection paths.
The operational impact of CVE-2023-22641 extends beyond simple redirection attacks and can lead to significant compromise of network security posture. When exploited, this vulnerability enables attackers to perform credential harvesting through phishing redirects, where users are tricked into entering authentication details on malicious sites that appear legitimate. The open redirect can also facilitate malware distribution by redirecting users to sites hosting malicious payloads, or enable more sophisticated attacks such as cross-site scripting exploitation when combined with other vulnerabilities. Organizations utilizing affected Fortinet appliances face potential data breaches, unauthorized access to sensitive networks, and compromise of critical infrastructure security controls. The attack vector typically involves an authenticated user session being manipulated through crafted HTTP requests that leverage the vulnerability to redirect to attacker-controlled domains, potentially leading to complete system compromise when combined with additional attack techniques.
Security mitigations for CVE-2023-22641 should prioritize immediate patching of all affected Fortinet products to the latest available versions that contain the necessary security fixes. Network administrators must also implement additional controls such as strict URL validation policies, monitoring for unusual redirect patterns, and implementing web application firewalls to detect and block malicious redirect attempts. Organizations should conduct comprehensive vulnerability assessments to identify all instances of affected Fortinet appliances within their network infrastructure and ensure proper access controls are in place to limit the attack surface. The remediation process should include thorough testing of patches in controlled environments before deployment to production systems, as well as monitoring for any signs of exploitation attempts. Additionally, security teams should review and enhance their incident response procedures to address potential exploitation of this vulnerability and implement network segmentation to limit the potential impact of successful attacks. This vulnerability also highlights the importance of adhering to security best practices such as input validation, principle of least privilege, and regular security updates to prevent similar issues from occurring in the future.