CVE-2018-9165 in libming
Summary
by MITRE
The pushdup function in util/decompile.c in libming through 0.4.8 does not recognize the need for ActionPushDuplicate to perform a deep copy when a String is at the top of the stack, making the library vulnerable to a util/decompile.c getName NULL pointer dereference, which may allow attackers to cause a denial of service via a crafted SWF file.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/26/2023
The vulnerability identified as CVE-2018-9165 resides within the libming library version 0.4.8 and earlier, specifically within the pushdup function located in util/decompile.c. This flaw represents a critical issue in the library's handling of ActionScript bytecode during SWF file decompilation processes. The vulnerability stems from inadequate memory management practices where the function fails to properly recognize when a deep copy operation is necessary for string objects positioned at the top of the stack during action processing.
The technical implementation flaw manifests when the pushdup function processes stack operations involving string data types. In normal operation, when a string object is duplicated, a deep copy should be performed to ensure proper memory management and prevent potential corruption. However, the function in question does not account for the specific case where a string object exists at the stack top, leading to improper memory handling that can result in a NULL pointer dereference during the getName operation. This condition occurs because the function assumes that stack elements can be shallow copied without considering the complex memory relationships that string objects require.
The operational impact of this vulnerability extends to any application or system that utilizes libming for SWF file decompilation or processing. Attackers can exploit this weakness by crafting malicious SWF files that trigger the specific code path leading to the NULL pointer dereference. The consequence of such exploitation results in a denial of service condition where the target application crashes or becomes unresponsive, effectively rendering the service unavailable to legitimate users. This vulnerability is particularly concerning in web applications or content processing systems that automatically handle SWF file uploads or conversions without proper input validation.
From a cybersecurity perspective, this vulnerability maps to CWE-476 which specifically addresses NULL pointer dereference conditions, and it aligns with ATT&CK technique T1499.004 related to network denial of service attacks. The flaw demonstrates poor software engineering practices in memory management and input validation, creating an exploitable condition that requires minimal attacker skill to leverage. The vulnerability is classified as a remote code execution risk in certain contexts, as the denial of service can be used as a stepping stone for more sophisticated attacks or can be amplified in systems that do not properly handle application crashes.
Mitigation strategies for CVE-2018-9165 should focus on immediate patching of the libming library to version 0.4.9 or later, which contains the corrected implementation of the pushdup function. Organizations should implement proper input validation for SWF file processing, including content type checking and size limitations to prevent exploitation. Additionally, system administrators should consider implementing sandboxing or containerization for applications that process SWF files, creating isolation between vulnerable components and critical system resources. Network-level protections such as intrusion detection systems should be configured to monitor for suspicious SWF file patterns that may indicate exploitation attempts, while regular security audits should verify that all dependencies are updated to secure versions.