CVE-2018-8962 in libming
Summary
by MITRE
In libming 0.4.8, the decompileSingleArgBuiltInFunctionCall function of decompile.c has a use-after-free. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted swf file.
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Analysis
by VulDB Data Team • 02/24/2023
The vulnerability identified as CVE-2018-8962 resides within the libming library version 0.4.8, specifically within the decompileSingleArgBuiltInFunctionCall function located in the decompile.c source file. This issue represents a classic use-after-free vulnerability that occurs when a program continues to reference memory after it has been freed, creating potential for unpredictable behavior and system instability. The libming library serves as a SWF (Small Web Format) file manipulation library that allows developers to create and modify Flash content, making it a critical component in multimedia applications and web development environments.
The technical flaw manifests during the processing of SWF files when the decompileSingleArgBuiltInFunctionCall function handles certain function calls that contain single arguments. When a crafted SWF file triggers this specific code path, the function frees a memory allocation but subsequently continues to reference the freed memory location during the decompilation process. This memory access violation occurs because the program fails to properly track the memory state after deallocation, allowing for potential exploitation through malformed input data that causes the application to execute code against already freed memory segments. The vulnerability specifically affects the library's ability to safely parse and process SWF files, particularly those containing complex function call structures.
The operational impact of this vulnerability extends beyond simple denial of service, as remote attackers can leverage the use-after-free condition to potentially execute arbitrary code or cause system crashes. When a vulnerable application processes a maliciously crafted SWF file, the improper memory handling can lead to heap corruption, which may result in application instability, unexpected termination, or in more severe cases, arbitrary code execution within the context of the running process. This makes the vulnerability particularly dangerous in web environments where SWF files are commonly processed, as attackers can exploit this through web browsers or Flash player implementations that utilize the libming library for content manipulation. The remote exploitability aspect means that attackers do not require local access to the system, making it a significant threat vector for web-based attacks.
Mitigation strategies for CVE-2018-8962 should prioritize immediate patching of the libming library to version 0.4.9 or later, which contains the necessary memory management fixes. System administrators should implement proper input validation and sanitization for all SWF file processing, particularly in web applications where user-uploaded content is handled. Network-based mitigations can include implementing content filtering rules that block or scan SWF files at network boundaries, though this approach may impact legitimate functionality. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and represents a potential pathway for exploitation under the ATT&CK framework's technique T1059 for command and control through application layer protocols. Organizations should also consider implementing sandboxing mechanisms for SWF file processing and monitoring for unusual memory access patterns that might indicate exploitation attempts.