CVE-2017-8401 in SWFTools
Summary
by MITRE
In SWFTools 0.9.2, an out-of-bounds read of heap data can occur in the function png_load() in lib/png.c:724. This issue can be triggered by a malformed PNG file that is mishandled by png2swf. Attackers could exploit this issue for DoS.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-8401 represents a critical out-of-bounds read flaw within SWFTools version 0.9.2, specifically manifesting in the png_load() function located in lib/png.c at line 724. This issue arises from improper handling of malformed PNG files during the conversion process from PNG to SWF format through the png2swf utility. The flaw demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read vulnerabilities that occur when a program accesses memory beyond the boundaries of a buffer or array. The vulnerability is particularly concerning as it can be triggered by simply processing a specially crafted PNG file, making it an attractive target for attackers seeking to exploit the software without requiring complex attack vectors.
The technical implementation of this vulnerability stems from inadequate bounds checking within the png_load() function, which fails to properly validate the dimensions and structure of input PNG data before attempting to read from heap-allocated memory regions. When a malformed PNG file is processed, the function attempts to access memory locations that extend beyond the allocated buffer boundaries, potentially leading to memory corruption or system instability. This type of vulnerability falls under the broader category of memory safety issues and can be classified as a buffer over-read condition according to ATT&CK framework's T1059.007 technique for command and scripting interpreter, though the primary impact here is in the memory management layer rather than direct execution.
The operational impact of CVE-2017-8401 extends beyond simple denial-of-service conditions, as it represents a potential pathway for more sophisticated attacks. While the immediate effect is likely to cause the png2swf utility to crash or become unresponsive when processing malicious input files, the underlying memory corruption could theoretically be exploited to achieve arbitrary code execution under certain conditions. This makes the vulnerability particularly dangerous in environments where SWFTools is used to process untrusted content, such as web applications, content management systems, or automated conversion services. The vulnerability's exploitation potential increases when considering that PNG files are commonly used in web applications and can be easily embedded in various contexts, providing multiple attack surfaces for threat actors.
Mitigation strategies for CVE-2017-8401 should prioritize immediate software updates to versions that have addressed this specific vulnerability, as SWFTools 0.9.2 has been superseded by newer releases containing proper bounds checking mechanisms. Organizations should implement strict input validation procedures for any PNG files processed through SWFTools, including preliminary checks for file integrity and structure validation before conversion operations. Additionally, deployment of network-based intrusion detection systems can help identify attempts to exploit this vulnerability through malformed file uploads. The implementation of sandboxed processing environments for file conversion operations provides an additional layer of protection, isolating the vulnerable software from critical system resources. Security teams should also consider disabling or restricting the use of png2swf functionality in production environments until proper patches are verified and deployed, aligning with ATT&CK's defensive techniques for reducing attack surface and implementing least privilege access controls.