CVE-2018-12547 in OpenJ9
Summary
by MITRE
In Eclipse OpenJ9, prior to the 0.12.0 release, the jio_snprintf() and jio_vsnprintf() native methods ignored the length parameter. This affects existing APIs that called the functions to exceed the allocated buffer. This functions were not directly callable by non-native user code.
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Analysis
by VulDB Data Team • 07/09/2023
The vulnerability identified as CVE-2018-12547 resides within the Eclipse OpenJ9 runtime environment, specifically impacting versions prior to the 0.12.0 release. This issue manifests in the jio_snprintf() and jio_vsnprintf() native methods which serve as critical components for string formatting operations within the Java runtime. The flaw represents a classic buffer overflow vulnerability that occurs when the length parameter specifying the maximum number of characters to write is disregarded during string formatting operations. These functions are part of the internal native code implementation that interfaces between the Java Virtual Machine and the underlying operating system, making them essential for various runtime operations including logging, error reporting, and system message generation.
The technical implementation of this vulnerability stems from improper handling of buffer boundaries within the native C code that implements these string formatting functions. When applications or the JVM itself invoke these functions, they expect the length parameter to act as a safety mechanism preventing buffer overflows by limiting the number of characters written to the destination buffer. However, due to the flaw in the implementation, the length parameter is completely ignored, allowing the functions to write beyond the allocated memory space. This behavior creates a potential for memory corruption that could lead to unpredictable application behavior, system instability, or even allow for exploitation by malicious actors. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though it manifests in a more complex scenario involving native code interaction within a JVM environment.
The operational impact of this vulnerability extends beyond simple memory corruption, as it affects the fundamental stability and security posture of systems running affected versions of Eclipse OpenJ9. Applications relying on the JVM's string formatting capabilities could experience crashes, data corruption, or inconsistent behavior when these functions are invoked. The vulnerability is particularly concerning because it operates at the native code level within the JVM, meaning that even legitimate applications could be affected by buffer overflows that could potentially be leveraged for more sophisticated attacks. The fact that these functions are not directly callable by non-native user code suggests that exploitation would require specific conditions or indirect methods, but the potential for system-wide impact remains significant. This vulnerability directly impacts the integrity of the JVM's memory management and could compromise the security of applications running on affected systems.
Mitigation strategies for CVE-2018-12547 primarily focus on upgrading to Eclipse OpenJ9 version 0.12.0 or later, where the implementation has been corrected to properly respect the length parameter in jio_snprintf() and jio_vsnprintf() functions. Organizations should also implement comprehensive monitoring to detect any unusual application behavior or crashes that might indicate buffer overflow conditions. Security teams should consider implementing additional runtime protections such as stack canaries or address space layout randomization to provide additional defense-in-depth measures. The vulnerability aligns with ATT&CK technique T1059.007 for application execution and T1068 for exploit for privilege escalation, though exploitation would require specific conditions. System administrators should also review and validate all applications using Eclipse OpenJ9 to ensure compatibility with the corrected implementation, as the change in behavior could potentially affect applications that were relying on the flawed implementation. Regular security assessments and vulnerability scanning should include verification of the OpenJ9 runtime version to prevent exploitation of this and similar native code vulnerabilities.