CVE-2019-6728 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to disclose sensitive information on vulnerable installations of Foxit Reader. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the processing of PDF files. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated buffer. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the current process. Was ZDI-CAN-7353.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/04/2023
The vulnerability identified as CVE-2019-6728 represents a critical buffer over-read flaw in Foxit Reader version 10.0.1 and earlier, classified under CWE-125 as "Out-of-Bounds Read." This security issue affects the PDF processing engine within the popular document viewer application, creating a significant attack surface for remote threat actors. The vulnerability stems from insufficient input validation mechanisms when parsing maliciously crafted PDF files, specifically during the handling of user-supplied data structures. Attackers can exploit this weakness by crafting specially designed PDF documents that trigger the buffer over-read condition, potentially leading to information disclosure and code execution. The flaw requires user interaction to be successfully exploited, meaning victims must either visit a malicious webpage hosting the crafted PDF or directly open the malicious file, making it a typical client-side attack vector.
The technical implementation of this vulnerability occurs during the PDF parsing process where Foxit Reader fails to properly validate the boundaries of allocated memory buffers when processing certain PDF objects. When the application encounters malformed data structures within PDF files, particularly within embedded objects or streams, it attempts to read memory locations beyond the allocated buffer boundaries. This improper validation allows attackers to potentially access sensitive information from adjacent memory regions, including stack contents, heap data, or other process memory segments. The read past the end of buffer condition creates a situation where the application's memory access patterns become unpredictable, potentially exposing cryptographic keys, authentication tokens, or other confidential data stored in memory. This behavior aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript', as PDF files often contain embedded scripting capabilities that can be leveraged to exploit such memory corruption vulnerabilities.
The operational impact of CVE-2019-6728 extends beyond simple information disclosure, as the buffer over-read condition can be chained with other vulnerabilities to achieve remote code execution within the context of the Foxit Reader process. This makes the vulnerability particularly dangerous in enterprise environments where PDF documents are frequently shared and opened by multiple users. The attack vector through web browsers or email attachments means that organizations cannot simply rely on network-level protections, as the vulnerability can be triggered through legitimate document consumption activities. Security researchers have noted that the exploitability of this vulnerability increases when combined with other memory corruption issues, potentially allowing attackers to escalate privileges or bypass security controls. The vulnerability affects not only individual users but also organizations that depend on Foxit Reader for document processing, creating widespread potential impact across various industries including finance, healthcare, and government sectors where PDF document handling is common.
Organizations should implement immediate mitigations including updating to Foxit Reader version 10.1.0 or later, which contains patches addressing this vulnerability. Network administrators should consider implementing web application firewalls and content filtering solutions to block suspicious PDF files from entering the network perimeter. Additionally, user education programs should emphasize the importance of avoiding untrusted PDF documents and verifying document sources before opening. Security teams should monitor for exploitation attempts through network logs and endpoint detection systems, as the buffer over-read behavior may generate unusual memory access patterns that can be detected by security monitoring tools. The vulnerability highlights the importance of proper memory management and input validation in document processing applications, aligning with security best practices outlined in the OWASP Top Ten and NIST cybersecurity guidelines for preventing memory corruption vulnerabilities. Regular security assessments of document processing software should be conducted to identify similar buffer-related issues that could potentially be exploited by threat actors.