CVE-2018-13375 in FortiAnalyzer
Summary
by MITRE
An Improper Neutralization of Script-Related HTML Tags in Fortinet FortiAnalyzer 5.6.0 and below and FortiManager 5.6.0 and below allows an attacker to send DHCP request containing malicious scripts in the HOSTNAME parameter. The malicious script code is executed while viewing the logs in FortiAnalyzer and FortiManager (with FortiAnalyzer feature enabled).
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Analysis
by VulDB Data Team • 06/16/2020
This vulnerability represents a critical cross-site scripting flaw in Fortinet's network security management platforms, specifically affecting FortiAnalyzer and FortiManager versions up to 5.6.0. The issue stems from inadequate input validation and sanitization of the HOSTNAME parameter within DHCP request processing, creating an environment where malicious actors can inject arbitrary script code that persists in the system's log records. The vulnerability is classified under CWE-79 as an improper neutralization of script-related HTML tags, which directly enables persistent cross-site scripting attacks. When administrators view logs containing these malicious scripts, the embedded code executes within their browser context, potentially compromising the security of the management interface and enabling further attack vectors.
The technical exploitation occurs through the manipulation of DHCP request packets where attackers craft malicious HOSTNAME values containing script payloads. These payloads are stored in the system's database and displayed in log views without proper HTML escaping or sanitization. The vulnerability affects both FortiAnalyzer and FortiManager platforms, with the FortiAnalyzer feature enabled in FortiManager creating a particularly dangerous scenario where logs from multiple devices are aggregated and displayed in a single interface. This design flaw means that a single compromised device can potentially deliver malicious payloads to multiple administrators, amplifying the impact of the attack. The vulnerability's persistence is enhanced by the fact that the malicious code is stored in the database and executed each time logs are viewed, creating a continuous attack surface.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to steal administrative credentials, perform unauthorized configuration changes, or establish persistent access to the network management infrastructure. The attack requires minimal privileges to execute since DHCP requests are typically accepted by network infrastructure without strict validation, making the exploitation surface quite broad. Administrators who regularly review logs for security monitoring purposes become unwitting participants in the attack chain, as their browser sessions become compromised when viewing affected log entries. This vulnerability directly maps to ATT&CK technique T1059.007 for scripting and T1566.002 for phishing, as it enables both code execution and social engineering attacks through the log viewing interface. The persistent nature of the vulnerability means that even if the initial DHCP request is not actively monitored, the malicious code continues to execute whenever administrators access the affected log data, creating an ongoing threat that can persist long after the initial compromise.
Mitigation strategies should focus on immediate patching of affected Fortinet products to versions that properly sanitize input parameters and implement robust HTML escaping mechanisms. Network administrators should also consider implementing additional logging controls and access restrictions to limit exposure, while monitoring for unusual DHCP request patterns that might indicate exploitation attempts. The implementation of web application firewalls and content security policies can provide additional protection layers, though these are secondary measures to the core patching requirement. Regular security assessments of network management interfaces should include verification of input sanitization practices and review of log data for signs of injection attempts. Organizations should also establish incident response procedures specifically addressing persistent XSS vulnerabilities in network management systems, as these attacks can remain undetected for extended periods while continuing to compromise administrator sessions.