CVE-2021-34340 in libming
Summary
by MITRE • 03/10/2022
Ming 0.4.8 has an out-of-bounds buffer access issue in the function decompileINCR_DECR() in decompiler.c file that causes a direct segmentation fault and leads to denial of service.
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Analysis
by VulDB Data Team • 03/13/2022
The vulnerability identified as CVE-2021-34340 resides within the Ming library version 0.4.8, specifically manifesting in the decompileINCR_DECR() function located within the decompiler.c source file. This issue represents a classic buffer overflow condition that occurs when the software attempts to access memory locations beyond the allocated buffer boundaries during the decompilation process of certain bytecode sequences. The Ming library serves as a multimedia library for handling various file formats including swf and svg, making this vulnerability particularly concerning for applications that process untrusted multimedia content.
The technical flaw stems from inadequate bounds checking within the decompileINCR_DECR() function which processes increment and decrement operations during bytecode decompilation. When malformed or maliciously crafted input data is processed through this function, the code fails to validate array indices or buffer limits before performing memory access operations. This direct violation of memory safety principles results in a segmentation fault that terminates the executing process abruptly, effectively causing a denial of service condition for the affected application. The vulnerability operates at the binary level where the program attempts to read or write to memory locations that are not properly allocated or accessible, triggering the operating system's memory protection mechanisms.
From an operational perspective, this vulnerability presents a significant risk to applications that rely on the Ming library for processing multimedia content, particularly those handling untrusted user input or third-party files. The denial of service impact can be severe in environments where continuous availability is critical, such as web servers processing user-uploaded files or content management systems handling multimedia assets. Attackers could exploit this vulnerability by crafting specially formatted multimedia files designed to trigger the buffer overflow condition during the decompilation phase, leading to application crashes and potential system instability. The vulnerability's exploitation requires minimal privileges and can be executed through standard input processing workflows without requiring complex attack chains or additional system compromise.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a specific instance of improper input validation during decompilation processes. From an attack framework perspective, this vulnerability could be categorized under the software exploitation phase of the MITRE ATT&CK framework, specifically within the context of code injection or denial of service attacks. The attack surface is primarily limited to applications utilizing the Ming library and processing multimedia content, but the impact extends to any system where the library is integrated, potentially affecting web applications, desktop software, and server environments. Organizations should prioritize updating to patched versions of the Ming library or implementing input validation measures to prevent exploitation of this buffer overflow condition.
Mitigation strategies should include immediate patching of the Ming library to version 0.4.9 or later where the buffer overflow has been addressed through proper bounds checking implementation. Additionally, applications should implement robust input validation and sanitization mechanisms to prevent malformed content from reaching the vulnerable decompilation functions. System administrators should consider implementing sandboxing techniques and privilege separation to limit the impact of potential exploitation. Monitoring and logging should be enhanced to detect unusual application behavior that might indicate attempted exploitation of this vulnerability, particularly during multimedia content processing activities. Regular security assessments and dependency updates should be maintained to prevent similar vulnerabilities from emerging in other components of the software stack.