CVE-2018-14690 in SubSonic
Summary
by MITRE
An issue was discovered in Subsonic 6.1.1. The general settings are affected by two stored cross-site scripting vulnerabilities in the title and subtitle parameters to generalSettings.view that could be used to steal session information of a victim.
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Analysis
by VulDB Data Team • 03/26/2020
The vulnerability identified as CVE-2018-14690 represents a critical stored cross-site scripting flaw within the Subsonic media server version 6.1.1. This issue resides in the general settings functionality where the title and subtitle parameters of the generalSettings.view endpoint are not properly sanitized, allowing attackers to inject malicious scripts that persist in the application's database. The vulnerability specifically affects the administrative configuration interface where system administrators can modify general settings including the title and subtitle displayed throughout the application. When these parameters are processed and rendered without adequate input validation and output encoding, they create an environment where malicious code can be executed in the context of any user who views the affected settings page. The stored nature of this vulnerability means that once malicious input is submitted, it remains persistent in the database and will be executed every time the affected page is accessed by any authenticated user with sufficient privileges.
The technical exploitation of this vulnerability follows a well-established XSS attack pattern where an attacker crafts malicious input containing javascript payloads within the title and subtitle fields of the general settings. When an authenticated administrator or other user with appropriate privileges loads the generalSettings.view page, the malicious script executes in their browser context, potentially stealing session cookies, performing unauthorized actions, or redirecting users to malicious sites. This vulnerability directly maps to CWE-79 which defines Cross-Site Scripting as a weakness where applications fail to properly validate or encode user-controllable data that is then rendered in web pages. The attack vector operates through the standard web application request flow where parameters are passed through HTTP requests to the server-side processing logic, which fails to sanitize the inputs before storing them for later retrieval and display.
The operational impact of CVE-2018-14690 extends beyond simple script execution as it provides attackers with the capability to hijack administrative sessions and potentially gain full control over the Subsonic server. Since the affected parameters are part of the general settings accessible to administrators, successful exploitation could allow attackers to modify critical system configurations, access sensitive media libraries, or perform other administrative functions that compromise the entire media server infrastructure. The session theft aspect of this vulnerability particularly aligns with ATT&CK technique T1531 which focuses on Establishing Persistence through Session Hijacking and credential theft. The vulnerability affects the confidentiality and integrity of the system as unauthorized parties can gain access to administrative capabilities and potentially exfiltrate media content or modify system behavior. The persistence of the stored XSS means that the attack remains effective until the malicious input is removed from the database, making it particularly dangerous for long-term operations.
Mitigation strategies for CVE-2018-14690 should focus on implementing proper input validation and output encoding throughout the application's data flow. The most effective immediate solution involves sanitizing all user-controllable input parameters before storage and ensuring that any data rendered in web pages is properly encoded for the context in which it appears. This includes implementing Content Security Policy headers to limit script execution, using parameterized inputs where possible, and ensuring that all user-provided data undergoes strict validation before being stored in the database. Organizations should also implement regular security scanning of their Subsonic installations and apply the vendor-provided patch as soon as available. Additionally, implementing network segmentation and access controls can limit the potential impact of successful exploitation, while monitoring for unusual activity in the general settings modification logs can help detect unauthorized attempts to exploit this vulnerability. The remediation process should include thorough input validation that rejects or sanitizes any potentially malicious content before it is stored, and output encoding that prevents the execution of script code when displaying stored values in web interfaces.