CVE-2019-17639 in OpenJ9
Summary
by MITRE
In Eclipse OpenJ9 prior to version 0.21 on Power platforms, calling the System.arraycopy method with a length longer than the length of the source or destination array can, in certain specially crafted code patterns, cause the current method to return prematurely with an undefined return value. This allows whatever value happens to be in the return register at that time to be used as if it matches the method's declared return type.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/12/2024
The vulnerability identified as CVE-2019-17639 represents a critical flaw in the Eclipse OpenJ9 JVM implementation affecting Power platform architectures. This issue manifests specifically when the System.arraycopy method is invoked with parameters that exceed the bounds of either the source or destination arrays. The flaw operates at the intersection of memory management and method execution flow, creating a scenario where normal program execution can be disrupted through carefully constructed code patterns.
The technical root cause of this vulnerability stems from improper bounds checking within the System.arraycopy implementation on Power architectures. When an invalid length parameter is provided, the JVM's runtime execution engine fails to properly validate the array access boundaries before proceeding with the memory copying operation. This validation failure creates a path where the method execution can terminate prematurely, leaving the return register in an undefined state. The Power architecture's specific calling conventions and register usage patterns exacerbate this issue, as the return value is directly sourced from processor registers rather than being explicitly managed through stack operations.
From an operational perspective, this vulnerability presents significant security implications for applications running on affected OpenJ9 versions. The undefined return value behavior creates opportunities for information disclosure and potential code execution manipulation, as attackers can craft inputs that cause the method to return values from the processor's return register. This type of flaw falls under the CWE-129 weakness category, specifically addressing improper validation of array indices and bounds checking. The vulnerability's impact extends beyond simple data corruption, as it can be leveraged to manipulate program flow and potentially bypass security mechanisms that rely on predictable method return values.
The attack surface for this vulnerability is particularly concerning given the widespread use of Eclipse OpenJ9 in enterprise environments and cloud deployments. Attackers can exploit this flaw by constructing specific code patterns that trigger the premature return condition, potentially allowing them to extract sensitive information from memory or manipulate program execution paths. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as it can enable attackers to craft malicious code patterns that exploit the undefined behavior. The flaw also relates to privilege escalation vectors through code injection techniques, as the undefined return values could be manipulated to influence program logic in unexpected ways.
Mitigation strategies for this vulnerability require immediate deployment of Eclipse OpenJ9 version 0.21 or later, which contains the necessary bounds checking fixes. Organizations should also implement runtime monitoring to detect anomalous behavior patterns that might indicate exploitation attempts. Additional defensive measures include strengthening input validation processes and implementing code analysis tools that can identify potentially problematic array access patterns. System administrators should also consider implementing application whitelisting policies and monitoring for unusual memory access patterns that could indicate exploitation of this vulnerability. The fix addresses the underlying issue by implementing proper bounds validation before method execution, ensuring that array access operations cannot proceed beyond valid memory boundaries and preventing the premature return condition that leads to undefined behavior.