CVE-2018-8961 in libming
Summary
by MITRE
In libming 0.4.8, the decompilePUSHPARAM 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-2018-8961 represents a critical use-after-free flaw within the libming library version 0.4.8, specifically within the decompilePUSHPARAM function located in the decompile.c source file. This library serves as a SWF (Small Web Format) file manipulation tool widely used for processing and generating flash content, making it a potential target for exploitation in various security contexts. The flaw manifests when the library processes malformed SWF files that contain crafted PUSH parameter operations, leading to memory management issues that can be exploited by remote attackers.
The technical nature of this vulnerability stems from improper memory handling within the decompilePUSHPARAM function, where previously freed memory locations are accessed after the memory has been deallocated. This use-after-free condition occurs when the library attempts to process PUSH operations within SWF file structures without properly validating the memory state or ensuring that referenced memory blocks remain valid. The flaw is particularly dangerous because it can be triggered through remote file processing, allowing attackers to craft malicious SWF files that, when processed by vulnerable applications using libming, will cause the memory management system to attempt accessing freed memory regions.
The operational impact of CVE-2018-8961 extends beyond simple denial of service, as it creates potential for more severe consequences including arbitrary code execution in vulnerable environments. When exploited, this vulnerability can cause applications utilizing libming to crash or behave unpredictably, effectively rendering them unavailable to legitimate users. The remote exploitation capability means that attackers do not need physical access to target systems, as they can simply deliver malicious SWF content through web browsers, email attachments, or file sharing platforms. This vulnerability particularly affects web applications, content management systems, and any software that processes SWF files from untrusted sources, making it a significant concern for organizations maintaining web-facing services.
Organizations should implement immediate mitigations including updating to libming versions that contain patches for this vulnerability, typically version 0.4.9 or later, which address the memory management issues in the decompilePUSHPARAM function. Additionally, input validation should be strengthened at application layers that process SWF files, implementing strict file format checking and sanitization procedures before any processing occurs. Network-level protections such as web application firewalls and content filtering systems should be configured to block or scan SWF file uploads and downloads, particularly from untrusted sources. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and represents a typical example of how improper memory management can create exploitable conditions in software libraries that handle complex binary formats. From an ATT&CK framework perspective, this vulnerability maps to techniques involving remote code execution and privilege escalation through software exploitation, particularly in the context of web application attacks and file processing vulnerabilities.