CVE-2018-20247 in Quick PDF Library
Summary
by MITRE
In Foxit Quick PDF Library (all versions prior to 16.12), issue where loading a malformed or malicious PDF containing a recursive page tree structure using the LoadFromFile, LoadFromString or LoadFromStream functions results in a stack overflow.
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Analysis
by VulDB Data Team • 04/24/2020
The vulnerability identified as CVE-2018-20247 represents a critical stack overflow condition within Foxit Quick PDF Library versions prior to 16.12. This flaw manifests when the library processes malformed PDF files containing recursive page tree structures through its core loading functions including LoadFromFile, LoadFromString, and LoadFromStream. The recursive nature of the page tree structure causes the library's parsing algorithm to enter an infinite recursive loop, consuming system stack memory until exhaustion occurs. This behavior directly violates the principle of input validation and proper resource management that security standards such as CWE-674 mandate for robust software development practices.
The technical implementation of this vulnerability stems from insufficient bounds checking and recursion depth limitations within the PDF parsing engine of Foxit Quick PDF Library. When a maliciously crafted PDF file contains circular references or nested page tree structures that reference themselves or create loops, the library's recursive parsing functions fail to detect and terminate these problematic structures. The parsing routine continues to push new stack frames onto the call stack without proper termination conditions, leading to rapid stack consumption and eventual system crash. This type of vulnerability falls under the category of denial of service attacks and can be classified as a stack-based buffer overflow according to ATT&CK framework technique T1499.2.001, where the attacker leverages memory corruption to disrupt system functionality.
The operational impact of this vulnerability extends beyond simple service disruption, as it creates potential entry points for more sophisticated attacks. An attacker could exploit this weakness to cause application crashes, system instability, or even potentially execute arbitrary code if the stack overflow leads to memory corruption that can be manipulated. The vulnerability affects any application that utilizes Foxit Quick PDF Library for PDF processing, including document management systems, web applications, and enterprise software solutions that depend on PDF rendering capabilities. Organizations running affected versions of Foxit Quick PDF Library face significant risk of service degradation and potential system compromise, particularly in environments where PDF processing is a critical function.
Mitigation strategies for CVE-2018-20247 primarily focus on immediate version upgrades to Foxit Quick PDF Library 16.12 or later, which incorporates proper recursion detection and stack depth limiting mechanisms. Security teams should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additionally, organizations should consider implementing input validation measures at the application level, including PDF file size limits, content scanning, and sandboxed processing environments for PDF files from untrusted sources. Network segmentation and monitoring solutions should be deployed to detect potential exploitation attempts. The vulnerability highlights the importance of adhering to secure coding practices and implementing proper error handling mechanisms, as outlined in industry standards such as the OWASP Secure Coding Practices and the CERT Secure Coding Standards. Organizations should also conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in their PDF processing pipelines and other document handling components.