CVE-2020-11894 in libming
Summary
by MITRE
Ming (aka libming) 0.4.8 has a heap-based buffer over-read (8 bytes) in the function decompileIF() in decompile.c.
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Analysis
by VulDB Data Team • 06/01/2024
The vulnerability identified as CVE-2020-11894 affects the Ming library version 0.4.8, specifically within the decompileIF() function located in decompile.c. This represents a heap-based buffer over-read condition that occurs when processing certain input data structures. The flaw manifests as an 8-byte over-read, meaning that the function attempts to access memory locations that extend 8 bytes beyond the allocated buffer boundaries. Such buffer over-read vulnerabilities typically arise from inadequate bounds checking during memory operations and can lead to information disclosure or system instability.
The technical implementation of this vulnerability stems from improper input validation within the decompileIF() function which handles conditional statement decompilation. When the library processes malformed or specially crafted input files, the function fails to properly verify array bounds before accessing memory locations. This flaw aligns with CWE-125, which specifically addresses out-of-bounds read conditions in software implementations. The vulnerability exists because the code does not sufficiently validate the size or structure of input data before performing memory operations, creating a scenario where an attacker can manipulate input to trigger the over-read behavior.
Operationally, this vulnerability poses significant risks to systems utilizing the Ming library for processing swf file content. An attacker could potentially craft malicious swf files that, when processed by vulnerable applications, would cause the decompileIF() function to read beyond allocated memory boundaries. This could result in information leakage from adjacent memory regions, potentially exposing sensitive data such as stack contents, heap metadata, or other application information. The impact extends beyond simple information disclosure as such vulnerabilities often serve as precursors to more serious exploits, particularly when combined with other memory corruption issues. The vulnerability could be leveraged in a broader attack chain, potentially enabling privilege escalation or remote code execution depending on the target application's memory layout and protection mechanisms.
Mitigation strategies for CVE-2020-11894 should prioritize immediate patching of the Ming library to version 0.4.9 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should implement robust input validation measures and consider deploying defensive programming practices such as bounds checking, memory sanitization, and stack canaries to reduce the attack surface. The vulnerability demonstrates the importance of adhering to secure coding practices as outlined in the software security principles and aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution, as exploitation may involve crafting malicious inputs to trigger the vulnerable code path. Additionally, implementing application whitelisting and privilege separation can help limit the potential impact of successful exploitation attempts, while regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other components of the software ecosystem.