CVE-2024-3933 in Open J9
Summary
by MITRE • 05/27/2024
In Eclipse OpenJ9 release versions prior to 0.44.0 and after 0.13.0, when running with JVM option -Xgc:concurrentScavenge, the sequence generated for System.arrayCopy on the IBM Z platform with hardware and software support for guarded storage [1], could allow access to a buffer with an incorrect length value when executing an arraycopy sequence while the Concurrent Scavenge Garbage Collection cycle is active and the source and destination memory regions for arraycopy overlap. This allows read and write to addresses beyond the end of the array range.
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Analysis
by VulDB Data Team • 01/10/2025
The vulnerability described in CVE-2024-3933 affects the Eclipse OpenJ9 JVM implementation and represents a critical memory safety issue that manifests specifically on IBM Z platform systems. This flaw exists in versions of OpenJ9 between 0.13.0 and 0.44.0, creating a condition where the garbage collection mechanism interacts improperly with memory operations during concurrent scavenging cycles. The issue is particularly concerning because it leverages hardware features designed for memory protection, specifically guarded storage capabilities that are intended to prevent unauthorized memory access patterns.
The technical root cause stems from improper handling of arraycopy operations when the JVM operates with the -Xgc:concurrentScavenge option enabled. During active Concurrent Scavenge garbage collection cycles, when the source and destination memory regions for arraycopy operations overlap, the system generates incorrect sequence instructions that fail to properly validate the buffer length parameters. This occurs specifically on IBM Z platforms that support both hardware and software guarded storage features, creating a scenario where memory access validation is bypassed. The flaw results in the system reading from and writing to memory addresses that extend beyond the legitimate bounds of the array being manipulated.
The operational impact of this vulnerability is severe and potentially exploitable by malicious actors who can leverage the improper memory access patterns to achieve arbitrary read and write operations. An attacker could potentially access sensitive data beyond array boundaries, leading to information disclosure or memory corruption that might enable privilege escalation. The vulnerability specifically targets the interaction between concurrent garbage collection and memory protection mechanisms, creating a condition where the system's built-in safeguards are effectively neutralized during critical memory operations. This type of flaw falls under CWE-121, which describes stack-based buffer overflow conditions, though the actual mechanism here involves heap memory manipulation through garbage collection interactions.
The exploitation of this vulnerability requires specific conditions including the use of the concurrent scavenging garbage collection option, overlap between source and destination memory regions in arraycopy operations, and execution on IBM Z platforms with guarded storage support. The attack surface is limited to applications that utilize the -Xgc:concurrentScavenge JVM flag and perform arraycopy operations with overlapping memory regions while running on affected OpenJ9 versions. From an ATT&CK framework perspective, this vulnerability maps to techniques involving memory injection and privilege escalation, as the flaw enables unauthorized memory access patterns that could be used to manipulate application state or extract sensitive information.
Mitigation strategies include upgrading to Eclipse OpenJ9 version 0.44.0 or later, which contains the necessary fixes for the concurrent scavenging implementation. Organizations should also consider disabling the -Xgc:concurrentScavenge JVM option if concurrent scavenging is not critical to application performance, as this would eliminate the vulnerable code path. Additionally, monitoring systems should be enhanced to detect unusual memory access patterns that might indicate exploitation attempts. Security teams should prioritize patching systems running affected OpenJ9 versions, particularly those handling sensitive data or operating in high-risk environments where the vulnerability could be leveraged for data exfiltration or system compromise. The fix addresses the core issue by correcting the sequence generation logic for arraycopy operations during concurrent garbage collection cycles, ensuring proper validation of buffer lengths regardless of memory region overlaps.