CVE-2019-11772 in OpenJ9
Summary
by MITRE
In Eclipse OpenJ9 prior to 0.15, the String.getBytes(int, int, byte[], int) method does not verify that the provided byte array is non-null nor that the provided index is in bounds when compiled by the JIT. This allows arbitrary writes to any 32-bit address or beyond the end of a byte array within Java code run under a SecurityManager.
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Analysis
by VulDB Data Team • 11/01/2023
The vulnerability identified as CVE-2019-11772 affects Eclipse OpenJ9 versions prior to 0.15 and represents a critical security flaw in the Java Virtual Machine implementation. This issue specifically targets the String.getBytes(int, int, byte[], int) method which is commonly used for character encoding operations within Java applications. The vulnerability stems from insufficient input validation within the Just-In-Time compilation process, creating a potential pathway for unauthorized memory manipulation that can be exploited even when applications are running under security restrictions.
The technical flaw manifests when the JIT compiler processes the String.getBytes method without performing essential null checks on the target byte array parameter or bounds validation on the index parameters. This omission creates a scenario where malicious code can manipulate memory addresses directly through the method's parameters, allowing for arbitrary writes to any 32-bit memory address. The vulnerability becomes particularly dangerous when applications are executed under a SecurityManager, as the typical protections provided by this security mechanism are bypassed due to the unchecked memory access patterns. The flaw operates at the JVM level, making it potentially exploitable across various Java applications that utilize string encoding operations.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables attackers to perform sophisticated memory manipulation attacks that could lead to privilege escalation, code execution, or data compromise. When applications run with SecurityManager enabled, the expectation is that certain memory operations are restricted, but this vulnerability effectively nullifies those protections by allowing direct memory writes through the compromised method. The attack surface includes any Java application that performs string encoding operations using the affected getBytes method, particularly those running in environments where security restrictions are enforced. This vulnerability can be particularly devastating in server environments where applications process untrusted input and rely on JVM security mechanisms for protection.
Mitigation strategies for CVE-2019-11772 primarily focus on upgrading to Eclipse OpenJ9 version 0.15 or later, where the necessary input validation has been implemented. Organizations should prioritize immediate patching of all systems running affected versions, particularly those with applications that process external input or operate in security-sensitive environments. Additionally, defensive programming practices should be implemented to validate all array parameters before calling the getBytes method, and runtime monitoring should be enhanced to detect unusual memory access patterns. The vulnerability aligns with CWE-125, which addresses out-of-bounds read conditions, and represents a variant of memory corruption vulnerabilities that can be leveraged for privilege escalation attacks. From an ATT&CK perspective, this vulnerability maps to techniques involving memory injection and privilege escalation, making it a significant concern for organizations maintaining security posture against advanced persistent threats.