CVE-2018-9282 in Media Server
Summary
by MITRE
An XSS issue was discovered in Subsonic Media Server 6.1.1. The podcast subscription form is affected by a stored XSS vulnerability in the add parameter to podcastReceiverAdmin.view; no administrator access is required. By injecting a JavaScript payload, this flaw could be used to manipulate a user's session, or elevate privileges by targeting an administrative user.
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Analysis
by VulDB Data Team • 03/26/2020
The vulnerability identified as CVE-2018-9282 represents a critical stored cross-site scripting flaw within the Subsonic Media Server version 6.1.1, specifically affecting the podcast subscription functionality. This vulnerability exists in the podcastReceiverAdmin.view servlet where the add parameter is processed without adequate input validation or output encoding, creating a persistent vector for malicious code injection. The flaw is particularly concerning because it operates without requiring administrative privileges, making it accessible to any authenticated user within the system. The vulnerability stems from the server's failure to properly sanitize user-supplied input before storing and subsequently rendering it within the web interface, creating a direct pathway for attackers to inject malicious JavaScript code that persists across user sessions.
The technical exploitation of this vulnerability follows a specific attack pattern where an attacker crafts a malicious JavaScript payload and submits it through the podcast subscription form's add parameter. When the server processes this input and stores it in its database or configuration files, the payload becomes part of the application's persistent state. Subsequently, when any user accesses the podcast subscription interface, the malicious code executes within their browser context, potentially allowing attackers to hijack user sessions, steal cookies, or perform actions on behalf of the victim. This stored XSS vulnerability operates at the application layer and can be leveraged for privilege escalation when targeting administrative users, as the malicious code can potentially access administrative functions or extract sensitive information from the victim's session. The vulnerability directly maps to CWE-79 which defines cross-site scripting flaws as weaknesses that allow attackers to inject malicious scripts into web applications viewed by other users.
The operational impact of this vulnerability extends beyond simple session manipulation to potentially enable complete system compromise when administrative accounts are targeted. An attacker could craft payloads that redirect users to malicious domains, steal authentication tokens, or even inject additional malicious code that could lead to further exploitation within the network. The persistent nature of stored XSS means that the vulnerability remains active until the malicious content is removed from the system, potentially allowing attackers to maintain access for extended periods. The attack surface is broad as any user with access to the podcast subscription functionality could become a victim, making this particularly dangerous in environments where multiple users interact with the media server. This vulnerability also aligns with several ATT&CK techniques including T1059 for command and scripting interpreter and T1531 for use of web shell, as the injected JavaScript could be used to establish persistent access or exfiltrate data. Organizations utilizing Subsonic Media Server 6.1.1 face significant risk of unauthorized access and data compromise, particularly if administrative users interact with the podcast subscription features.
Mitigation strategies for CVE-2018-9282 require immediate implementation of proper input validation and output encoding mechanisms within the podcastReceiverAdmin.view servlet. The most effective immediate fix involves sanitizing all user input parameters, particularly the add parameter, before storing them in the application's data store and ensuring that any stored content is properly escaped when rendered in the user interface. Organizations should implement Content Security Policy headers to limit the execution of inline scripts and restrict the sources from which scripts can be loaded. Additionally, the application should validate input length, character sets, and encoding to prevent injection attacks. Regular security audits and code reviews should be conducted to identify similar vulnerabilities in other parts of the application. The recommended long-term solution includes upgrading to a patched version of Subsonic Media Server that addresses this specific vulnerability, as well as implementing comprehensive input validation frameworks that follow OWASP secure coding practices. Network segmentation and monitoring for suspicious traffic patterns related to podcast subscription activities can serve as additional defensive measures to detect and prevent exploitation attempts.