CVE-2021-27309 in Clansphere
Summary
by MITRE • 03/24/2021
Clansphere CMS 2011.4 allows unauthenticated reflected XSS via "module" parameter.
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Analysis
by VulDB Data Team • 04/04/2021
The vulnerability identified as CVE-2021-27309 affects Clansphere CMS version 2011.4 and represents a critical security flaw that enables unauthenticated reflected cross-site scripting attacks. This vulnerability resides within the application's parameter handling mechanism, specifically targeting the "module" parameter which is susceptible to malicious input injection. The flaw allows attackers to inject malicious scripts that execute in the context of victim browsers without requiring any authentication credentials, making it particularly dangerous for public-facing web applications.
The technical implementation of this vulnerability stems from inadequate input validation and output sanitization within the CMS framework. When the application processes the "module" parameter without proper sanitization, it directly incorporates user-supplied data into the HTTP response without adequate encoding or filtering. This creates an environment where malicious scripts can be executed in the victim's browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The reflected nature of this XSS vulnerability means that the malicious payload is reflected back to the user through the web application's normal response mechanism, making it particularly effective for phishing attacks and social engineering campaigns.
The operational impact of this vulnerability extends beyond simple script execution, as it can be leveraged for more sophisticated attacks within the context of the targeted application. Attackers can exploit this flaw to steal user sessions, modify content displayed to authenticated users, or redirect victims to malicious domains that appear legitimate. The unauthenticated nature of this vulnerability means that any user visiting a maliciously crafted URL containing the XSS payload can be compromised without requiring valid credentials. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1566.001 for credential access through spearphishing campaigns that can be enhanced by this XSS capability. Organizations running Clansphere CMS 2011.4 are particularly at risk as the vulnerability affects the core application functionality and can be exploited through various attack vectors including email campaigns, compromised websites, or social media platforms.
Mitigation strategies for CVE-2021-27309 should prioritize immediate patching of the affected CMS version, as this represents the most effective defense against the vulnerability. Organizations should implement comprehensive input validation and output encoding mechanisms to prevent malicious data from being processed or displayed within the application. The implementation of Content Security Policy headers can provide an additional layer of protection by restricting script execution and preventing unauthorized code injection. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within the application stack, while web application firewalls can be configured to detect and block known XSS attack patterns. Additionally, user education regarding suspicious links and email attachments remains crucial in preventing successful exploitation attempts, particularly when combined with proper application security controls. The vulnerability demonstrates the importance of maintaining up-to-date software versions and implementing robust security practices throughout the application lifecycle to prevent such critical flaws from being exploited in production environments.