CVE-2000-0563 in MacOS Runtime Java
Summary
by MITRE
The URLConnection function in MacOS Runtime Java (MRJ) 2.1 and earlier and the Microsoft virtual machine (VM) for MacOS allows a malicious web site operator to connect to arbitrary hosts using a HTTP redirection, in violation of the Java security model.
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Analysis
by VulDB Data Team • 04/06/2019
The vulnerability identified as CVE-2000-0563 represents a critical security flaw in the Java runtime environments of MacOS systems, specifically affecting MacOS Runtime Java (MRJ) 2.1 and earlier versions along with the Microsoft virtual machine for MacOS. This weakness stems from improper handling of HTTP redirection mechanisms within the Java security model, creating a pathway for malicious actors to circumvent security boundaries that should normally prevent unauthorized network connections. The flaw fundamentally undermines the sandboxing principles that Java implementations rely upon to protect users from potentially harmful network operations.
The technical implementation of this vulnerability lies in how the URLConnection function processes HTTP redirects within the affected Java runtime environments. When a malicious website attempts to establish a connection to another host through a redirect, the vulnerable implementation fails to properly validate or restrict the destination of these redirects. This allows attackers to craft web pages that redirect users to arbitrary hosts, effectively bypassing the security restrictions that should prevent Java applets from making unauthorized network connections. The vulnerability specifically exploits the trust model where the runtime environment should enforce security boundaries but instead permits connections to hosts outside the originally requested domain.
The operational impact of this vulnerability extends beyond simple network connectivity issues, as it provides attackers with the capability to perform unauthorized network reconnaissance and potentially establish connections to internal systems that should remain isolated from external access. Attackers can leverage this flaw to create malicious web pages that redirect users to command and control servers, facilitate data exfiltration, or perform other malicious activities without the user's knowledge or consent. The security model violation means that legitimate security measures designed to protect users from unauthorized network access become ineffective, creating a significant risk for users who browse the web with vulnerable Java implementations.
Mitigation strategies for CVE-2000-0563 require immediate updates to the affected Java runtime environments, with users upgrading to patched versions of MRJ and the Microsoft virtual machine for MacOS. System administrators should disable Java applet execution in web browsers where possible, as this removes the attack surface entirely. Network administrators should implement firewall rules and proxy configurations to restrict outbound connections from Java applications, though this approach provides only partial protection since the vulnerability exists at the runtime level. The vulnerability aligns with CWE-284, which addresses improper access control in software systems, and relates to ATT&CK technique T1071.004 for application layer protocol: DNS, as it enables unauthorized network communications that bypass normal security controls. Organizations should also consider implementing network monitoring to detect unusual outbound connections that may indicate exploitation attempts, particularly focusing on connections to unexpected hosts or unusual protocols.