CVE-2009-3881 in OpenJDK
Summary
by MITRE
Sun Java SE 5.0 before Update 22 and 6 before Update 17, and OpenJDK, does not prevent the existence of children of a resurrected ClassLoader, which allows remote attackers to gain privileges via unspecified vectors, related to an "information leak vulnerability," aka Bug Id 6636650.
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Analysis
by VulDB Data Team • 08/27/2021
The vulnerability described in CVE-2009-3881 represents a critical security flaw in Sun Java SE and OpenJDK implementations that stems from improper handling of ClassLoader resurrection mechanisms. This issue affects Java SE versions 5.0 before Update 22 and 6 before Update 17, as well as OpenJDK implementations, creating a persistent security risk that can be exploited remotely. The vulnerability is categorized under CWE-264, which addresses permissions, privileges, and access control issues, specifically within the context of Java security mechanisms. The flaw manifests when a ClassLoader is resurrected, allowing child objects to persist in memory even after the parent ClassLoader has been garbage collected, creating an information leak that can be leveraged by attackers.
The technical implementation of this vulnerability exploits the Java Virtual Machine's memory management and class loading mechanisms. When a ClassLoader is destroyed and subsequently resurrected, the JVM fails to properly clean up child objects that were associated with the original ClassLoader instance. This creates a scenario where objects from the previous ClassLoader context can persist in memory and potentially be accessed or manipulated by unauthorized code. The vulnerability specifically relates to the information leak aspect where sensitive data or object references that should have been cleaned up remain accessible, enabling attackers to gain unauthorized privileges. This behavior violates the fundamental security principles of Java's security model, which relies on proper isolation between different ClassLoader contexts to prevent privilege escalation attacks.
The operational impact of this vulnerability is significant as it allows remote attackers to exploit the information leak for privilege escalation attacks within Java applications. Attackers can leverage this weakness to access objects or data that should be isolated within specific ClassLoader contexts, potentially enabling them to execute unauthorized code or gain elevated privileges within the Java runtime environment. The vulnerability affects applications that rely on dynamic class loading and unloading, particularly those implementing security-sensitive features or applications that use custom ClassLoader implementations. This flaw can be particularly dangerous in web applications, enterprise systems, and any environment where Java applications handle sensitive data or implement security controls that depend on proper ClassLoader isolation.
Mitigation strategies for this vulnerability require immediate patching of affected Java installations to the recommended updates, specifically Java SE 5.0 Update 22 and Java SE 6 Update 17, which contain the necessary fixes for the ClassLoader resurrection issue. Organizations should implement comprehensive monitoring to detect any unusual ClassLoader behavior or unexpected object retention patterns within their Java applications. Security hardening measures should include restricting the use of dynamic class loading where possible, implementing proper memory management practices, and ensuring that all Java applications are running on patched versions of the runtime environment. Additionally, organizations should conduct regular security assessments of their Java applications to identify potential exploitation vectors and implement proper access controls and privilege management to minimize the impact of such vulnerabilities. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the use of information disclosure for privilege escalation purposes, making it a critical concern for enterprise security teams implementing Java-based solutions.