CVE-2017-12906 in NexusPHP
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in NexusPHP allow remote attackers to inject arbitrary web script or HTML via the PATH_INFO to (1) cheaters.php or (2) confirm_resend.php.
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Analysis
by VulDB Data Team • 11/13/2019
The vulnerability identified as CVE-2017-12906 represents a critical cross-site scripting flaw within the NexusPHP application framework that exposes users to significant security risks. This vulnerability resides in the handling of PATH_INFO parameters within two specific script files, cheaters.php and confirm_resend.php, which are commonly used in torrent management systems and similar web applications. The flaw allows remote attackers to inject malicious web scripts or HTML code directly into the application's response, creating persistent XSS vectors that can compromise user sessions and data integrity.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding mechanisms within the NexusPHP codebase. When the application processes PATH_INFO parameters through the affected endpoints, it fails to properly sanitize user-supplied data before incorporating it into dynamically generated HTML responses. This omission creates an exploitable condition where attackers can craft malicious URLs containing script payloads that execute in the context of authenticated users' browsers. The vulnerability specifically affects the cheaters.php and confirm_resend.php scripts, which are typically used for user verification and administrative functions within the torrent management ecosystem.
From an operational perspective, the impact of this vulnerability extends beyond simple script injection to potentially enable session hijacking, credential theft, and data exfiltration attacks. When users with valid credentials access the vulnerable endpoints with maliciously crafted PATH_INFO parameters, their browsers execute the injected scripts, which could redirect them to malicious sites, steal session cookies, or modify application behavior. The attack surface is particularly concerning given that these endpoints often handle sensitive user data and administrative functions, making them attractive targets for threat actors seeking persistent access to the underlying system.
The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and demonstrates characteristics consistent with ATT&CK technique T1566.001, which involves the exploitation of web application vulnerabilities to execute malicious code. Security professionals should consider this vulnerability as part of a broader attack surface assessment that includes input validation weaknesses and output encoding deficiencies. The remediation approach should focus on implementing proper parameter validation, input sanitization, and output encoding mechanisms that prevent user-supplied data from being interpreted as executable code within the application context.
Mitigation strategies for CVE-2017-12906 require immediate implementation of proper input validation and output encoding practices throughout the NexusPHP application. Developers should ensure that all PATH_INFO parameters are validated against expected formats and sanitized before processing, while also implementing proper HTML encoding for any user-supplied data that appears in response content. Additionally, organizations should consider implementing web application firewalls to detect and block suspicious PATH_INFO patterns, while conducting regular security assessments to identify similar vulnerabilities in other application components. The fix should align with security best practices outlined in OWASP Top Ten and NIST Cybersecurity Framework guidelines for web application security.