CVE-2018-7866 in newVar3
Summary
by MITRE
A NULL pointer dereference was discovered in newVar3 in util/decompile.c in libming 0.4.8. The vulnerability causes a segmentation fault and application crash, which leads to denial of service.
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Analysis
by VulDB Data Team • 02/17/2023
The vulnerability identified as CVE-2018-7866 represents a critical NULL pointer dereference flaw within the libming library version 0.4.8, specifically within the newVar3 function located in the util/decompile.c source file. This issue manifests as a segmentation fault during application execution, ultimately resulting in a complete denial of service condition that can be exploited by malicious actors to disrupt system operations. The libming library serves as a SWF file manipulation tool that processes and decompiles flash content, making this vulnerability particularly concerning for applications that rely on proper handling of multimedia files.
The technical nature of this flaw stems from inadequate input validation and error handling within the decompilation process. When the newVar3 function processes certain malformed or unexpected input data structures, it fails to properly check for NULL pointer conditions before attempting to dereference memory addresses. This fundamental programming error creates a condition where the application attempts to access memory at address zero, triggering a segmentation fault that terminates the process abruptly. The vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference issues in software applications, and demonstrates poor defensive programming practices that violate secure coding principles.
The operational impact of CVE-2018-7866 extends beyond simple application crashes to encompass broader system availability concerns. When exploited successfully, this vulnerability can cause denial of service across any system that utilizes libming for SWF file processing, including web applications, content management systems, and multimedia processing platforms. Attackers can craft malicious SWF files that trigger the NULL pointer dereference, leading to persistent service disruptions that may require system restarts to resolve. This makes the vulnerability particularly attractive for denial of service attacks targeting web services that process user-uploaded flash content, as it allows for remote exploitation without requiring elevated privileges or complex attack vectors.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected libming installations to version 0.4.9 or later, which contains the necessary code modifications to properly handle NULL pointer conditions. Additionally, implementing input validation measures that sanitize all SWF file content before processing can provide defense-in-depth protection against similar issues. System administrators should consider deploying intrusion detection systems that monitor for suspicious SWF file patterns and implement proper application sandboxing to limit the impact of potential exploitation attempts. The vulnerability also highlights the importance of regular security assessments and code reviews to identify similar NULL pointer dereference conditions that may exist in other parts of the software ecosystem, aligning with ATT&CK technique T1499.004 for defensive measures against application denial of service conditions.