CVE-2016-3740 in Foxit
Summary
by MITRE
Heap-based buffer overflow in the CreateFXPDFConvertor function in ConvertToPdf_x86.dll in Foxit Reader 7.3.4.311 allows remote attackers to execute arbitrary code via a large SamplesPerPixel value in a crafted TIFF image that is mishandled during PDF conversion. This is fixed in 8.0.
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Analysis
by VulDB Data Team • 08/25/2020
The vulnerability identified as CVE-2016-3740 represents a critical heap-based buffer overflow flaw within Foxit Reader version 7.3.4.311, specifically within the ConvertToPdf_x86.dll component. This vulnerability manifests in the CreateFXPDFConvertor function where improper input validation leads to memory corruption when processing specially crafted TIFF image files. The flaw occurs during the PDF conversion process where a maliciously constructed TIFF image containing an excessively large SamplesPerPixel value triggers the buffer overflow condition. The vulnerability is classified under CWE-121 as a heap-based buffer overflow, which is a well-documented weakness in memory management where data written beyond allocated buffer boundaries can overwrite adjacent memory locations. This particular vulnerability demonstrates a classic example of improper input validation where the application fails to properly sanitize or limit the size of the SamplesPerPixel parameter during TIFF image processing, creating a potential execution path for remote code execution.
The operational impact of this vulnerability is severe and directly relates to the remote code execution capabilities it provides to attackers. When a user opens or converts a specially crafted TIFF image through Foxit Reader, the malicious SamplesPerPixel value causes the application to write beyond the allocated heap buffer space, potentially overwriting critical memory structures including return addresses, function pointers, or other control data. This memory corruption can be exploited to redirect program execution flow to malicious code injected into the heap memory space, effectively allowing remote attackers to execute arbitrary code with the privileges of the affected application. The vulnerability affects the PDF conversion functionality specifically, meaning that even if users don't directly open the malicious TIFF file, simply initiating the conversion process within Foxit Reader can trigger the exploit. This aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries leverage vulnerabilities in applications to execute malicious code on victim systems. The vulnerability is particularly concerning because it requires no user interaction beyond the standard PDF conversion workflow, making it highly exploitable in real-world scenarios.
The remediation for this vulnerability requires immediate upgrading to Foxit Reader version 8.0 or later, which contains the necessary patches to address the buffer overflow condition. The fix implemented in version 8.0 involves proper input validation and bounds checking for the SamplesPerPixel parameter during TIFF image processing, ensuring that values are properly constrained before being used in memory allocation operations. Security practitioners should implement comprehensive patch management policies to ensure all instances of Foxit Reader are updated promptly, as the vulnerability affects multiple deployment environments including enterprise networks, educational institutions, and individual users. Additionally, organizations should consider implementing network-based protections such as intrusion prevention systems that can detect and block suspicious TIFF file transfers, though the most effective mitigation remains the application of the vendor-provided security patches. The vulnerability serves as a reminder of the importance of proper input validation and memory safety practices in software development, particularly for applications handling untrusted file formats and user-provided content. Organizations should also consider implementing sandboxing techniques and application whitelisting to limit the potential impact of similar vulnerabilities in other applications, as the underlying principles of heap overflow exploitation remain consistent across different software platforms and architectures.