CVE-2017-3131 in FortiOS
Summary
by MITRE
A Cross-Site Scripting vulnerability in Fortinet FortiOS versions 5.4.0 through 5.4.4 and 5.6.0 allows attackers to execute unauthorized code or commands via the filter input in "Applications" under FortiView.
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Analysis
by VulDB Data Team • 09/08/2024
The vulnerability described in CVE-2017-3131 represents a critical cross-site scripting flaw within Fortinet FortiOS operating systems that affects versions 5.4.0 through 5.4.4 and 5.6.0. This weakness resides in the web interface of the FortiOS system, specifically within the FortiView module's Applications section where user input is improperly validated and sanitized. The vulnerability manifests when an attacker submits malicious script code through the filter input field, which then gets executed in the context of other users who access the affected web interface. This particular flaw falls under CWE-79 which defines Cross-Site Scripting vulnerabilities as a result of insufficient input validation and output encoding. The attack vector is particularly concerning as it leverages the administrative web interface of a network security device, potentially allowing threat actors to escalate privileges and gain unauthorized access to sensitive network infrastructure.
The technical implementation of this vulnerability stems from inadequate sanitization of user-provided input within the FortiView Applications filter functionality. When users interact with the web-based management interface of FortiOS, the system fails to properly encode or escape special characters in filter parameters before rendering them in the web response. This allows malicious payloads to be injected and subsequently executed in the browser contexts of legitimate users who view the affected application data. The exploitation requires minimal privileges as the vulnerability exists within the web interface itself, making it accessible to both authenticated and unauthenticated attackers depending on the specific configuration. Attackers can craft malicious filter parameters that contain javascript or other scripting languages which execute in the victim's browser when the filtered results are displayed, potentially leading to session hijacking, data exfiltration, or further exploitation of the network device.
The operational impact of CVE-2017-3131 extends beyond simple script execution as it represents a significant threat to network security infrastructure integrity. An attacker who successfully exploits this vulnerability could potentially gain access to administrative functions of the FortiOS device, leading to complete compromise of the network security appliance. The vulnerability affects FortiView's Applications section which provides visibility into network traffic patterns and application usage, making it a valuable target for reconnaissance and data collection. Additionally, the compromised device could serve as a pivot point for further attacks within the network, as FortiOS devices often act as gateways and security control points. This vulnerability directly impacts the principle of least privilege and could enable attackers to bypass security controls, making it particularly dangerous in enterprise environments where these devices serve as critical security infrastructure components. The attack could result in unauthorized access to sensitive network information, modification of security policies, or complete device compromise, all while maintaining the appearance of legitimate administrative activity.
Mitigation strategies for CVE-2017-3131 should include immediate deployment of Fortinet's official security patches and firmware updates addressing the specific cross-site scripting vulnerability. Organizations should implement network segmentation and access controls to limit exposure of FortiOS devices to untrusted networks, reducing the attack surface available to potential exploiters. Input validation and output encoding should be strengthened through web application firewalls and security monitoring solutions that can detect and block malicious script injection attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other network security devices and applications. The remediation process should also include comprehensive user training on recognizing potential phishing attempts and social engineering attacks that may leverage this vulnerability. According to ATT&CK framework, this vulnerability maps to T1059.007 for script execution and T1566 for social engineering techniques that could be employed to deliver malicious payloads. Organizations should also consider implementing network monitoring solutions that can detect anomalous behavior patterns consistent with exploitation attempts and establish incident response procedures specifically addressing web application vulnerabilities in network security infrastructure.