CVE-2011-0311 in Java
Summary
by MITRE
The class file parser in IBM Java before 1.4.2 SR13 FP9, as used in IBM Runtimes for Java Technology 5.0.0 before SR13 and 6.0.0 before SR10, allows remote authenticated users to cause a denial of service (JVM segmentation fault, and possibly memory consumption or an infinite loop) via a crafted attribute length field in a class file, which triggers a buffer over-read.
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Analysis
by VulDB Data Team • 11/18/2021
The vulnerability identified as CVE-2011-0311 represents a critical buffer over-read flaw within the class file parser of IBM Java Runtime environments. This issue affects multiple versions of IBM Java Technology Runtimes including versions 5.0.0 through SR12 and 6.0.0 through SR9, specifically before the release of IBM Java 1.4.2 SR13 FP9. The vulnerability stems from insufficient validation of attribute length fields within class files, creating a scenario where maliciously crafted class files can trigger unexpected behavior in the Java Virtual Machine. The flaw manifests when the parser encounters a malformed attribute length field that exceeds the bounds of allocated memory buffers, leading to potentially catastrophic system consequences.
The technical implementation of this vulnerability resides in the class file parsing mechanism that processes Java bytecode files. When the Java Virtual Machine encounters a class file with an improperly formatted attribute length field, the parser attempts to read beyond the allocated buffer boundaries, resulting in a segmentation fault that crashes the JVM process. This buffer over-read condition can also lead to memory exhaustion or infinite loop scenarios, depending on how the malformed data is processed by the parser. The vulnerability is classified under CWE-125 as an out-of-bounds read, which is a common vector for denial of service attacks in runtime environments. The flaw specifically affects the Java class file format parsing logic and demonstrates a classic example of insufficient input validation in security-critical components.
The operational impact of this vulnerability extends beyond simple denial of service conditions, potentially affecting the availability and stability of Java-based applications running on affected IBM JVM versions. Remote authenticated attackers with the ability to upload or execute malicious class files can exploit this vulnerability to crash JVM processes, leading to application downtime and service disruption. In enterprise environments where IBM Java Runtime is extensively used for business-critical applications, this vulnerability could result in significant operational impact including system unavailability, data processing interruptions, and potential financial losses. The vulnerability's classification under ATT&CK technique T1499.004 indicates its potential for causing denial of service through resource consumption, while also presenting opportunities for more sophisticated attack chains that could leverage the JVM instability for additional exploitation vectors.
Mitigation strategies for CVE-2011-0311 primarily focus on updating to patched versions of IBM Java Runtime environments. Organizations should immediately upgrade to IBM Java 1.4.2 SR13 FP9 or later for Java 5.0.0 environments, and IBM Java 6.0.0 SR10 or later for Java 6.0.0 environments. Additionally, implementing runtime restrictions such as limiting class file upload capabilities and validating all incoming class files through proper schema validation can provide additional defense in depth. Network segmentation and access controls should be enforced to limit the attack surface, while monitoring systems should be configured to detect unusual JVM termination patterns or memory consumption spikes that could indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation in security-critical components and highlights the necessity of regular security updates and patch management processes in enterprise environments.