CVE-2015-6509 in pfSense
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in pfSense before 2.2.3 allow remote attackers to inject arbitrary web script or HTML via the (1) proxypass parameter to system_advanced_misc.php; (2) adaptiveend, (3) adaptivestart, (4) maximumstates, (5) maximumtableentries, or (6) aliasesresolveinterval parameter to system_advanced_firewall.php; (7) proxyurl, (8) proxyuser, or (9) proxyport parameter to system_advanced_misc.php; or (10) name, (11) notification_name, (12) ipaddress, (13) password, (14) smtpipaddress, (15) smtpport, (16) smtpfromaddress, (17) smtpnotifyemailaddress, (18) smtpusername, or (19) smtppassword parameter to system_advanced_notifications.php.
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Analysis
by VulDB Data Team • 10/18/2017
The CVE-2015-6509 vulnerability represents a critical cross-site scripting flaw affecting pfSense versions prior to 2.2.3, exposing multiple attack vectors through various administrative configuration pages. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically targeting input validation mechanisms within pfSense's web-based administrative interface. The flaw enables remote attackers to execute malicious scripts in the context of authenticated users' browsers, potentially leading to complete system compromise and unauthorized access to sensitive network configurations.
The technical implementation of this vulnerability stems from insufficient sanitization of user-supplied input parameters across multiple administrative PHP scripts. Attackers can exploit this weakness by injecting malicious payloads through the proxypass parameter in system_advanced_misc.php, or through various parameters in system_advanced_firewall.php including adaptiveend, adaptivestart, maximumstates, maximumtableentries, and aliasesresolveinterval. Additionally, the vulnerability extends to system_advanced_misc.php with proxyurl, proxyuser, and proxyport parameters, as well as system_advanced_notifications.php where name, notification_name, ipaddress, password, smtpipaddress, smtpport, smtpfromaddress, smtpnotifyemailaddress, smtpusername, and smtppassword parameters can be manipulated.
The operational impact of this vulnerability is severe, as it allows attackers to execute arbitrary web scripts and HTML code within the browser context of authenticated administrators. This creates opportunities for session hijacking, privilege escalation, and potential lateral movement within the network infrastructure. An attacker who successfully exploits these vulnerabilities could gain administrative access to the pfSense firewall, potentially compromising the entire network security posture. The attack surface is particularly concerning given that these parameters are typically used for legitimate administrative configuration tasks, making the exploitation less obvious to security monitoring systems.
Mitigation strategies for CVE-2015-6509 require immediate patching of pfSense installations to version 2.2.3 or later, which includes proper input validation and sanitization measures. Organizations should also implement network segmentation and access controls to limit administrative access to pfSense interfaces, while deploying web application firewalls to detect and prevent exploitation attempts. The vulnerability demonstrates the importance of input validation in web applications and aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as attackers can execute malicious code through browser-based interfaces. Regular security assessments and code reviews should focus on identifying similar input validation weaknesses in other network security appliances and web applications to prevent similar vulnerabilities from being exploited in the future.