CVE-2009-3866 in JRE
Summary
by MITRE
The Java Web Start Installer in Sun Java SE in JDK and JRE 6 before Update 17 does not properly use security model permissions when removing installer extensions, which allows remote attackers to execute arbitrary code by modifying a certain JNLP file to have a URL field that points to an unintended trusted application, aka Bug Id 6872824.
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Analysis
by VulDB Data Team • 03/30/2025
The vulnerability described in CVE-2009-3866 represents a critical security flaw in the Java Web Start installer component of Sun Java SE JDK and JRE versions 6 before update 17. This issue stems from improper implementation of security model permissions during the removal of installer extensions, creating a pathway for remote attackers to execute arbitrary code through manipulation of JNLP files. The vulnerability specifically affects the trust model implementation within Java Web Start, which is designed to prevent unauthorized execution of applications by enforcing strict permission boundaries between different security zones.
The technical flaw manifests when the Java Web Start installer processes JNLP files and fails to properly validate or restrict the URL field within these files. Attackers can craft malicious JNLP files that contain a URL field pointing to unintended trusted applications, bypassing the normal security restrictions that should prevent execution of code from untrusted sources. This occurs because the installer does not adequately enforce the security permissions that should normally prevent extension removal operations from executing code outside of the intended trust boundaries. The vulnerability essentially allows an attacker to escalate privileges by leveraging the installer's insufficient permission checking mechanisms, enabling code execution with the privileges of the user running the installer.
The operational impact of this vulnerability is significant as it allows remote code execution attacks to be delivered through Java Web Start applications without requiring user interaction beyond downloading and executing a malicious JNLP file. This makes it particularly dangerous in enterprise environments where users may inadvertently download and execute malicious files from untrusted sources. The vulnerability affects the core security model of Java Web Start, potentially allowing attackers to execute malicious code with elevated privileges, compromise user systems, and potentially establish persistent access to target environments. The flaw is particularly concerning because it operates at the installer level, meaning it can potentially bypass higher-level security controls that would normally protect against such attacks.
Mitigation strategies for this vulnerability include applying the official security patch from Oracle that addresses the permission checking implementation in the Java Web Start installer. Organizations should also implement network-level controls to restrict access to Java Web Start applications and monitor for suspicious JNLP file downloads. Security professionals should consider disabling Java Web Start functionality where possible, especially in environments where it is not strictly required. The vulnerability aligns with CWE-264, which covers permissions, privileges, and access controls, and represents a specific instance of privilege escalation through improper access control mechanisms. From an ATT&CK perspective, this vulnerability maps to techniques involving privilege escalation and execution through trusted applications, making it a significant concern for defensive security operations.