CVE-2016-9827 in libming
Summary
by MITRE
The _iprintf function in outputtxt.c in the listswf tool in libming 0.4.7 allows remote attackers to cause a denial of service (buffer over-read) via a crafted SWF file.
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Analysis
by VulDB Data Team • 08/15/2020
The vulnerability identified as CVE-2016-9827 represents a critical buffer over-read flaw within the libming library version 0.4.7, specifically affecting the listswf tool's _iprintf function in the outputtxt.c module. This issue manifests when processing maliciously crafted SWF files, creating a remote denial of service condition that can be exploited by attackers without requiring local system access. The vulnerability stems from inadequate input validation and memory management within the SWF file parsing routine, where the _iprintf function fails to properly bounds-check data reads from malformed SWF content, leading to unauthorized memory access patterns.
The technical implementation of this vulnerability involves the _iprintf function's improper handling of structured data within SWF file headers and content sections. When the listswf tool encounters specially crafted SWF files containing malformed data sequences, the function attempts to read beyond allocated memory boundaries during text output generation. This buffer over-read condition occurs because the software does not validate the length or structure of embedded data before attempting to process it, creating a scenario where attacker-controlled input can trigger memory corruption. The flaw operates at the application layer and can be classified under CWE-125 as an out-of-bounds read, with potential implications for memory safety and system stability.
From an operational perspective, this vulnerability presents significant risk to systems that process SWF files, particularly those running applications built on or utilizing the libming library. The remote exploitation capability means that attackers can trigger the denial of service condition from outside the target network, making it particularly dangerous in web environments where SWF content is frequently processed. Systems that automatically parse or display SWF files, including web browsers with Flash plugin support, content management systems, and multimedia processing applications, could be affected. The impact extends beyond simple service disruption to potentially enabling more sophisticated attacks if combined with other vulnerabilities, as the memory corruption could provide opportunities for information disclosure or arbitrary code execution depending on the system architecture.
The attack surface for CVE-2016-9827 encompasses any application or system that utilizes the listswf tool from libming 0.4.7, particularly those processing untrusted SWF content. This includes web applications that convert SWF files to text representations, multimedia processing pipelines, and security analysis tools that examine Flash content. The vulnerability's classification aligns with ATT&CK technique T1059.007 for command and scripting interpreter usage, as exploitation involves manipulating file formats to trigger memory access violations. Organizations should consider implementing input validation controls and sandboxing mechanisms to prevent exploitation, while also ensuring all systems using libming are updated to patched versions or migrated to alternative libraries that properly handle malformed input data.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected libming installations to version 0.4.8 or later, where the buffer over-read issue has been addressed through proper bounds checking and input validation. System administrators should implement network segmentation and access controls to limit exposure of systems processing SWF files, while also deploying intrusion detection systems to monitor for exploitation attempts. Additionally, organizations should consider implementing file type validation and content scanning mechanisms to prevent processing of potentially malicious SWF files, particularly in environments where untrusted user input is processed. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability is fully resolved and that no regressions have been introduced in the software functionality.