CVE-2002-2102 in Jzlib
Summary
by MITRE
InfBlocks.java in JCraft JZlib before 0.0.7 allow remote attackers to cause a denial of service (NullPointerException) via an invalid block of deflated data.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/09/2024
The vulnerability identified as CVE-2002-2102 affects the JCraft JZlib library version 0.0.6 and earlier, specifically within the InfBlocks.java component responsible for handling decompression operations. This issue represents a classic denial of service vulnerability that can be exploited by remote attackers through manipulation of compressed data streams. The flaw manifests when the library processes invalid block structures within deflated data, leading to a NullPointerException that terminates the application process. The vulnerability falls under CWE-476 which categorizes NULL Pointer Dereference conditions, making it particularly dangerous in networked applications where compressed data is received from untrusted sources.
The technical implementation of this vulnerability stems from inadequate input validation within the decompression algorithm. When JZlib encounters malformed deflate blocks during the inflation process, the InfBlocks.java class fails to properly handle these exceptional conditions, resulting in an unhandled NullPointerException. This occurs because the decompression logic does not sufficiently validate the structure and content of compressed data blocks before attempting to access their internal components. The flaw is particularly insidious as it can be triggered through normal network traffic containing compressed data, requiring no special privileges or complex attack vectors. The vulnerability demonstrates poor error handling practices and lacks proper exception management mechanisms that would gracefully handle malformed input data.
From an operational perspective, this vulnerability poses significant risks to applications that rely on JZlib for decompression services, particularly web applications, file servers, and network protocols that utilize compression. Attackers can exploit this weakness by sending specifically crafted compressed data packets that contain invalid deflate blocks, causing the target system to crash or become unresponsive. The impact extends beyond simple service interruption as the vulnerability can be leveraged in distributed denial of service attacks where multiple targets are simultaneously overwhelmed. The vulnerability affects systems running any application that uses JCraft JZlib version 0.0.6 or earlier, making it particularly widespread in legacy systems and applications that have not been updated to newer versions.
The recommended mitigation strategy involves immediate upgrading to JCraft JZlib version 0.0.7 or later, which contains the necessary patches to address the NullPointerException issue. Organizations should also implement input validation mechanisms at network boundaries to filter out potentially malicious compressed data before it reaches vulnerable applications. Additionally, application-level monitoring should be deployed to detect unusual patterns of decompression failures that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and organizations should consider implementing defensive measures such as rate limiting and connection pooling to minimize the impact of potential exploitation attempts. Regular security assessments and dependency updates should be prioritized to prevent similar vulnerabilities from being present in production environments.