CVE-2017-10956 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 tile index member of SOT markers. 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-4978.
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Analysis
by VulDB Data Team • 12/16/2019
CVE-2017-10956 represents a critical information disclosure vulnerability affecting Foxit Reader version 8.3.1.21155 that demonstrates a classic buffer over-read condition within the software's handling of PDF SOT (Special Object Type) markers. This vulnerability operates under the Common Weakness Enumeration category CWE-125, which specifically addresses out-of-bounds read conditions that occur when software attempts to access memory locations beyond the allocated buffer boundaries. The flaw manifests in the tile index member of SOT markers, where insufficient input validation permits maliciously crafted PDF content to trigger memory access violations that expose sensitive data from adjacent memory regions.
The exploitation scenario requires user interaction through either visiting a malicious web page containing crafted PDF content or opening a specially prepared malicious file, making this a prime example of a client-side attack vector that aligns with ATT&CK technique T1203 - Exploitation for Client Execution. The vulnerability's impact extends beyond simple information disclosure as it creates potential for privilege escalation and code execution within the context of the current process, as noted in the vulnerability description. This occurs because the read past the end of an allocated object can expose memory addresses, cryptographic keys, or other sensitive information that an attacker could then leverage to construct more sophisticated attacks.
From a technical perspective, the vulnerability demonstrates poor memory management practices and inadequate bounds checking within the PDF parsing engine of Foxit Reader. When the software processes SOT markers containing malformed tile index data, it fails to validate the size or range of user-supplied data before attempting to read from memory locations. This weakness creates opportunities for attackers to craft PDF files that, when processed by the vulnerable software, cause the application to read beyond its intended memory boundaries. The resulting memory exposure can reveal stack contents, heap metadata, or other process-specific information that significantly aids in bypassing security mitigations such as ASLR (Address Space Layout Randomization) and DEP (Data Execution Prevention).
The operational impact of this vulnerability is substantial for organizations relying on Foxit Reader for document processing, as it represents a potential pathway for attackers to gain unauthorized access to sensitive information or establish persistent access within the victim environment. The vulnerability's classification as a remote attack vector means that adversaries can exploit it without physical access to target systems, making it particularly dangerous in enterprise environments where users frequently interact with untrusted PDF content from email attachments, web downloads, or document sharing platforms. Organizations should consider this vulnerability as part of a broader attack chain that could lead to complete system compromise when combined with other exploitation techniques, as indicated by the vulnerability's potential for code execution. Mitigation strategies should include immediate patching of affected Foxit Reader installations, implementation of PDF content filtering mechanisms, and user education regarding the dangers of opening untrusted PDF files from unknown sources.