CVE-2015-8766 in Symphony
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in content/content.systempreferences.php in Symphony CMS before 2.6.4 allow remote attackers to inject arbitrary web script or HTML via the (1) email_sendmail[from_name], (2) email_sendmail[from_address], (3) email_smtp[from_name], (4) email_smtp[from_address], (5) email_smtp[host], (6) email_smtp[port], (7) jit_image_manipulation[trusted_external_sites], or (8) maintenance_mode[ip_whitelist] parameters to system/preferences.
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Analysis
by VulDB Data Team • 07/02/2022
The vulnerability CVE-2015-8766 represents a critical cross-site scripting flaw in Symphony CMS version 2.6.3 and earlier, specifically affecting the content/systempreferences.php file. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is one of the most prevalent and dangerous web application security flaws. The flaw exists in the system preferences handling mechanism where user-supplied input is not properly sanitized before being rendered back to users, creating an avenue for malicious actors to execute arbitrary JavaScript code within the context of other users' browsers. The vulnerability impacts multiple email configuration parameters and maintenance mode settings, making it particularly dangerous as it can be exploited through various attack vectors within the CMS administration interface.
The technical exploitation of this vulnerability occurs when attackers manipulate the system preference parameters that control email sending capabilities and maintenance mode access. The vulnerable parameters include email_sendmail[from_name], email_sendmail[from_address], email_smtp[from_name], email_smtp[from_address], email_smtp[host], email_smtp[port], jit_image_manipulation[trusted_external_sites], and maintenance_mode[ip_whitelist]. When these parameters contain malicious script code and are processed by the CMS without proper input validation or output encoding, the injected code executes in the browser context of authenticated users who view the affected system preferences page. This creates a persistent XSS condition where attackers can establish backdoors, steal session cookies, perform unauthorized actions, or redirect users to malicious websites.
The operational impact of CVE-2015-8766 extends beyond simple script injection, as it can be leveraged for sophisticated attacks within the CMS environment. Attackers who successfully exploit this vulnerability can gain elevated privileges by executing malicious code in the context of admin users, potentially leading to complete system compromise. The vulnerability's reach is amplified because it affects core system configuration parameters that are frequently accessed and modified by administrators. The attack surface includes not only the direct injection points but also the potential for privilege escalation through session hijacking or credential theft. Additionally, the maintenance_mode[ip_whitelist] parameter presents a particularly dangerous attack vector as it could allow unauthorized users to bypass security measures and gain access to restricted system functions.
Mitigation strategies for CVE-2015-8766 require immediate implementation of input validation and output encoding measures. The primary fix involves upgrading Symphony CMS to version 2.6.4 or later, where the vulnerability has been patched through proper sanitization of user inputs. Organizations should implement comprehensive input validation that filters or escapes special characters in all system preference parameters, particularly those used in email configuration and access control settings. Output encoding should be applied when rendering any user-supplied data back to the browser to prevent script execution. Security practitioners should also consider implementing web application firewalls with XSS detection capabilities and conduct regular security audits of CMS configurations. The vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1213 for Credential Access through web application vulnerabilities, emphasizing the need for proper input sanitization and output encoding in all web applications.