CVE-2018-9036 in Canopy
Summary
by MITRE
CheckSec Canopy 3.x before 3.0.7 has stored XSS via the Login Page Disclaimer, allowing attacks by low-privileged users against higher-privileged users.
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Analysis
by VulDB Data Team • 02/20/2020
The vulnerability identified as CVE-2018-9036 affects CheckSec Canopy versions 3.x prior to 3.0.7, specifically targeting the Login Page Disclaimer functionality. This issue represents a stored cross-site scripting vulnerability that enables attackers to inject malicious scripts into the application's login interface. The flaw occurs when user-supplied input from the disclaimer field is not properly sanitized or validated before being stored in the application's database and subsequently rendered back to users during login attempts. Low-privileged users can exploit this weakness to inject malicious code that will execute in the context of higher-privileged users who view the disclaimer content, creating a significant security risk within the application's access control framework.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the Canopy application's disclaimer handling system. When administrators configure the login page disclaimer, the system accepts raw user input without proper sanitization processes that would neutralize potentially malicious script content. The stored nature of this vulnerability means that once malicious code is injected into the disclaimer field, it persists in the database and executes every time the login page is accessed by any user, regardless of their privilege level. This creates a persistent threat vector that can be leveraged to steal session cookies, perform unauthorized actions, or redirect users to malicious sites.
The operational impact of CVE-2018-9036 extends beyond simple script execution, as it fundamentally compromises the integrity of the application's authentication mechanism. Higher-privileged users who regularly access the login page become potential victims of this attack, making it particularly dangerous for administrators and other elevated privilege accounts. Attackers can craft malicious payloads that appear legitimate within the context of the application's login interface, making detection more difficult. The vulnerability also undermines the trust model of the application, as users may unknowingly execute malicious code when they encounter the disclaimer during login attempts. This type of vulnerability directly impacts the application's security posture by creating an attack surface that allows privilege escalation through social engineering and automated script injection techniques.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms throughout the application's data handling pipeline. The most effective immediate solution involves upgrading to CheckSec Canopy version 3.0.7 or later, which includes proper sanitization of user input in the disclaimer field. Organizations should also implement strict content security policies that prevent script execution in user-controllable fields and establish robust input validation that filters out potentially dangerous characters and script tags. Additionally, regular security audits should be conducted to identify and remediate similar vulnerabilities in other application components. From a defensive perspective, implementing web application firewalls with XSS detection capabilities and monitoring for unusual input patterns in administrative interfaces can provide additional layers of protection against exploitation attempts.
This vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws in software applications, and demonstrates the critical importance of proper input sanitization in web applications. The attack vector maps to ATT&CK technique T1059.007 for Scripting, where adversaries leverage stored XSS to execute malicious scripts. The vulnerability also relates to privilege escalation techniques in ATT&CK framework, as it allows low-privileged users to compromise higher-privileged accounts through the authentication interface. Organizations should consider implementing the principle of least privilege in their application configuration, limiting the ability of low-privileged users to modify critical interface elements like login page disclaimers. The remediation process should include comprehensive testing to ensure that all user-controllable interface elements properly sanitize input and encode output to prevent similar vulnerabilities from being introduced in future versions or related components.