CVE-2017-16574 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to disclose sensitive information on vulnerable installations of Foxit Reader 8.3.1.21155. 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 parsing of Image filters. 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 object. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the current process. Was ZDI-CAN-5079.
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Analysis
by VulDB Data Team • 12/16/2019
CVE-2017-16574 represents a critical information disclosure vulnerability affecting Foxit Reader version 8.3.1.21155 that operates under the CWE-125 weakness category, which describes out-of-bounds read conditions. This vulnerability resides within the PDF viewer's image filter parsing mechanism, where insufficient input validation allows attackers to manipulate memory access patterns. The flaw manifests when the application processes malformed image data within PDF documents, specifically during the handling of compressed image filters such as JPEG or FlateDecode. When a user visits a malicious webpage or opens a crafted PDF file containing specially constructed image data, the parser attempts to read memory locations beyond the bounds of allocated buffers. This memory corruption occurs because the application fails to properly validate the length and structure of image filter data before processing, creating a predictable pattern of buffer overread conditions.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a foundation for more severe exploitation techniques that align with ATT&CK technique T1059.007 for command and script interpreter. The out-of-bounds read condition enables attackers to extract sensitive data from adjacent memory regions, potentially including stack canaries, return addresses, or other process-specific information that could be leveraged for privilege escalation. When combined with other vulnerabilities present in the same application or system, this flaw can facilitate arbitrary code execution within the context of the Foxit Reader process. The requirement for user interaction through web browsing or file opening makes this vulnerability particularly dangerous in phishing campaigns or targeted attacks where social engineering plays a significant role.
Security researchers identified this vulnerability through careful analysis of the PDF parsing code within Foxit Reader's image handling components, specifically focusing on how the application processes different image filter types. The vulnerability's classification under ZDI-CAN-5079 indicates its recognition by the Zero Day Initiative vulnerability research program, highlighting its significance in the cybersecurity community. The exploitation requires precise manipulation of PDF image data structures to trigger the buffer overread condition, typically involving crafted JPEG or FlateDecode filter parameters that cause the parser to misinterpret data length specifications. Attackers can leverage this vulnerability by embedding malicious PDF content that, when processed by the vulnerable reader, triggers the memory access violation and potentially exposes sensitive information that could aid in further exploitation attempts.
Mitigation strategies for CVE-2017-16574 should focus on both immediate remediation and long-term security enhancements. Organizations must prioritize updating Foxit Reader installations to versions that address this vulnerability, as the vendor likely released patches specifically targeting the image filter parsing logic. Network-based protections such as web application firewalls and PDF content filtering systems can help detect and block malicious PDF files before they reach end users, though this approach relies on signature-based detection methods that may not catch all variants. Users should be educated about the risks of opening untrusted PDF files or visiting suspicious websites, as the vulnerability requires user interaction to exploit. System-level protections including address space layout randomization and data execution prevention can help mitigate potential exploitation attempts, while process isolation techniques can limit the impact should exploitation occur. Security monitoring should focus on detecting unusual PDF processing activities or memory access patterns that might indicate exploitation attempts, with particular attention to network traffic containing PDF files from unknown sources.