CVE-2018-6014 in SubSonic
Summary
by MITRE
Subsonic v6.1.3 has an insecure allow-access-from domain="*" Flash cross-domain policy that allows an attacker to retrieve sensitive user information via a read request. To exploit this issue, an attacker must convince the user to visit a web site loaded with a SWF file created specifically to steal user data.
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Analysis
by VulDB Data Team • 02/04/2020
The vulnerability identified as CVE-2018-6014 affects Subsonic version 6.1.3 and represents a critical security flaw in the application's cross-domain policy implementation. This issue stems from an insecure Flash cross-domain policy configuration that uses a wildcard domain specification of "domain=*" which permits unrestricted access from any domain. The vulnerability exists within the Flash Player's security model where cross-domain policy files control how Flash content can communicate with resources from different domains. When an application serves a cross-domain policy file with overly permissive settings, it creates an attack surface that malicious actors can exploit to bypass security boundaries and access sensitive data.
The technical flaw manifests through the improper configuration of the cross-domain policy file, specifically the allow-access-from directive that permits access from any domain without proper restrictions. This configuration allows any SWF file from any domain to make requests to the Subsonic server and potentially retrieve user information through read operations. The vulnerability requires a specific attack vector involving social engineering where an attacker must convince a victim to visit a malicious website containing a specially crafted SWF file. This file would then leverage the overly permissive cross-domain policy to make requests to the vulnerable Subsonic instance and extract sensitive user data.
The operational impact of this vulnerability is significant as it allows attackers to perform unauthorized data exfiltration from Subsonic installations. An attacker could potentially access user credentials, personal information, media library data, and other sensitive content stored within the Subsonic server. The attack requires user interaction through social engineering techniques, but once executed successfully, it provides a persistent means for data theft. The vulnerability affects the confidentiality and integrity of the system as it enables unauthorized access to user information without proper authentication or authorization mechanisms. This type of attack falls under the category of cross-site scripting and data exfiltration techniques that have been documented in various security frameworks including the OWASP Top Ten and MITRE ATT&CK framework under the data exposure and credential access categories.
The security implications extend beyond simple data theft to include potential privilege escalation and further attack surface expansion. Attackers could use the retrieved information to conduct more sophisticated attacks such as credential stuffing, identity theft, or to gain deeper access to the system. The vulnerability demonstrates poor security configuration practices and highlights the importance of proper security policy implementation. Organizations should implement the principle of least privilege in their cross-domain policy configurations and avoid using wildcard domains in security-sensitive applications. The issue aligns with CWE-941, which addresses insecure cross-domain policy configurations, and represents a failure to properly implement the security principle that access should be restricted to authorized domains only. Mitigation strategies should include immediate patching of the vulnerable Subsonic version, proper configuration of cross-domain policy files to restrict access to specific domains, and implementation of additional security monitoring to detect unauthorized access attempts. Regular security audits of application configurations and adherence to security best practices should be enforced to prevent similar vulnerabilities from occurring in the future.