CVE-2018-7868 in libming
Summary
by MITRE
There is a heap-based buffer over-read in the getName function of util/decompile.c in libming 0.4.8 for CONSTANT8 data. A Crafted input will lead to a denial of service attack.
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Analysis
by VulDB Data Team • 02/17/2023
The vulnerability identified as CVE-2018-7868 represents a critical heap-based buffer over-read flaw within the libming library version 0.4.8. This issue specifically manifests in the getName function located within the util/decompile.c file when processing CONSTANT8 data structures. The libming library serves as a SWF (Shockwave Flash) file manipulation library that allows developers to create and modify flash content programmatically. The vulnerability arises from inadequate input validation and bounds checking during the parsing of SWF file elements, particularly when handling constant pool entries that utilize the CONSTANT8 data type. The flaw occurs because the function fails to properly verify the boundaries of memory allocations when extracting name information from these specific data structures, leading to memory access violations that extend beyond allocated buffer limits.
The technical implementation of this vulnerability exploits the inherent weakness in memory management practices within the decompilation process. When the getName function processes CONSTANT8 data, it assumes a certain memory layout and data structure format that may not hold true for maliciously crafted inputs. The heap-based nature of the over-read indicates that the vulnerability operates on dynamically allocated memory regions, making it particularly dangerous as it can potentially corrupt heap metadata or trigger memory corruption that affects program stability. The attack vector requires a specifically crafted SWF file containing malformed CONSTANT8 data that, when processed by the vulnerable libming library, causes the getName function to read memory beyond its intended boundaries. This type of buffer over-read can result in unpredictable program behavior, application crashes, and in some cases could potentially be leveraged for more sophisticated attacks if combined with other vulnerabilities.
The operational impact of CVE-2018-7868 extends beyond simple denial of service conditions, as it represents a fundamental flaw in how the library handles potentially malicious input. Systems that rely on libming for SWF file processing, including web applications, content management systems, or any software that imports or manipulates flash content, become vulnerable to this attack. The vulnerability can be exploited by attackers who craft malicious SWF files designed to trigger the buffer over-read condition, leading to service disruption and potential system instability. From a cybersecurity perspective, this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and can be categorized under ATT&CK technique T1059.007 for scripting languages, as it affects applications that process scripting content through SWF files. The vulnerability's classification as a denial of service vector means that attackers can reliably cause systems to crash or become unresponsive, potentially affecting availability for legitimate users.
Mitigation strategies for CVE-2018-7868 require immediate attention through library version updates, as the vulnerability has been addressed in subsequent releases of libming. Organizations should prioritize upgrading to versions that contain the patched implementation of the getName function with proper bounds checking and input validation. Additionally, implementing input sanitization measures that validate SWF file structures before processing can provide an additional layer of defense, though this approach may not completely prevent exploitation given the nature of the heap corruption. Network-level defenses such as content filtering and SWF file validation can help reduce the attack surface by preventing potentially malicious files from reaching systems that utilize libming. Security monitoring should include detection of unusual application crashes or memory access patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the importance of robust memory management practices in C-based libraries and highlights the critical need for thorough input validation, particularly in applications that process untrusted binary data formats like SWF files.