CVE-2018-7872 in libming
Summary
by MITRE
An invalid memory address dereference was discovered in the function getName in libming 0.4.8 for CONSTANT16 data. 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-2018-7872 represents a critical memory safety issue within the libming library version 0.4.8, specifically affecting the processing of CONSTANT16 data structures. This flaw manifests in the getName function where improper handling of memory addresses leads to invalid memory access patterns that can be exploited to cause system instability. The libming library serves as a SWF file format library used for creating and manipulating Shockwave Flash content, making this vulnerability particularly concerning for applications that process untrusted SWF files or incorporate SWF rendering capabilities.
The technical root cause of this vulnerability stems from inadequate input validation and memory management within the getName function when processing CONSTANT16 data types. When the library encounters malformed or unexpected CONSTANT16 data structures, the function fails to properly validate memory pointers before dereferencing them, resulting in a segmentation fault. This type of vulnerability falls under the CWE-476 category of NULL Pointer Dereference, though specifically manifests as an invalid memory address dereference rather than a simple null pointer access. The flaw occurs during the parsing phase of SWF file processing, where the library attempts to extract name information from constant pools without sufficient bounds checking or memory address validation.
The operational impact of CVE-2018-7872 extends beyond simple application crashes to potentially enable more sophisticated attack vectors. Systems utilizing libming for SWF file processing become vulnerable to denial of service attacks where maliciously crafted SWF files can trigger the segmentation fault and cause application termination. This vulnerability is particularly dangerous in web applications or content management systems that automatically process user-uploaded SWF files, as it can be exploited to disrupt service availability for legitimate users. The attack surface is broad given that SWF files are still processed by various media players and web browsers, making this vulnerability relevant across multiple attack vectors including web-based exploitation and file processing scenarios.
Mitigation strategies for CVE-2018-7872 should prioritize immediate patching of the libming library to version 0.4.9 or later, which contains the necessary memory validation fixes. Organizations should implement input sanitization measures for all SWF file processing workflows, including validation of file headers and constant pool structures before parsing. Network-level defenses can include implementing file type validation and content filtering to prevent potentially malicious SWF files from reaching vulnerable applications. From an ATT&CK framework perspective, this vulnerability maps to the T1203 technique of Exploitation for Client Execution, where adversaries leverage memory corruption vulnerabilities to execute arbitrary code or cause service disruption. System administrators should also consider implementing process isolation and resource limits for applications that handle SWF file processing to minimize the impact of potential exploitation attempts. The vulnerability demonstrates the importance of memory safety practices in multimedia libraries and the critical need for comprehensive input validation in file format parsers.