CVE-2019-5590 in FortiWeb
Summary
by MITRE
The URL part of the report message is not encoded in Fortinet FortiWeb 6.0.2 and below which may allow an attacker to execute unauthorized code or commands (Cross Site Scripting) via attack reports generated in HTML form.
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Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2019-5590 affects Fortinet FortiWeb appliances running version 6.0.2 and earlier, representing a critical cross-site scripting weakness in the application layer. This flaw resides in how the system handles URL components within report messages, specifically when these reports are generated in HTML format. The root cause stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize URL parameters before incorporating them into HTML report content. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, where untrusted data is directly embedded into web pages without proper sanitization, creating opportunities for malicious code injection. The issue is particularly concerning in web application firewalls where the system generates reports containing user-supplied data that may contain malicious payloads.
The operational impact of this vulnerability extends beyond typical XSS scenarios, as it specifically targets the report generation functionality within FortiWeb's security framework. When an attacker can manipulate URL parameters within attack reports, they can potentially inject malicious scripts that execute in the context of legitimate users who view these reports. This creates a vector for privilege escalation and potential command execution within the web application environment. The vulnerability's exploitation becomes more severe when considering that FortiWeb appliances are designed to protect against such attacks, making the presence of XSS vulnerabilities within their own reporting mechanisms particularly ironic and dangerous. The HTML report generation process becomes a potential attack surface where malicious input can be stored and later executed when administrators or users view these reports.
Security researchers have identified this issue as a significant concern within the context of the ATT&CK framework, specifically relating to the execution of malicious code through web application vulnerabilities. The vulnerability demonstrates how defensive security tools can themselves contain weaknesses that attackers can leverage to bypass protection mechanisms. Organizations using affected FortiWeb versions face potential risks including data exfiltration, session hijacking, and unauthorized access to backend systems. The vulnerability's impact is amplified by the fact that these reports are typically viewed by security administrators who may have elevated privileges, providing attackers with potential access to sensitive operational data. Additionally, the vulnerability's presence in the reporting functionality means that even legitimate security events could become attack vectors.
Mitigation strategies for CVE-2019-5590 require immediate attention from affected organizations, beginning with upgrading to FortiWeb versions 6.0.3 or later where the vulnerability has been addressed. Network administrators should implement additional input validation measures at the perimeter level and consider disabling HTML report generation if the functionality is not critical to operations. Organizations should also review their existing security policies to ensure that report viewing privileges are properly restricted and that users accessing these reports follow least-privilege principles. The fix implemented by Fortinet addresses the core encoding issue in URL handling within report messages, ensuring that special characters and potentially malicious input are properly escaped before inclusion in HTML output. Security teams should conduct thorough vulnerability assessments to identify any potential exploitation attempts and monitor network traffic for indicators of compromise related to this vulnerability.