CVE-2017-14821 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 the xTsiz member of SIZ 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-5013.
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Analysis
by VulDB Data Team • 12/16/2019
CVE-2017-14821 represents a critical information disclosure vulnerability affecting Foxit Reader version 8.3.1.21155 that demonstrates the dangerous consequences of improper input validation in document processing software. This vulnerability resides within the parsing logic of the xTsiz member within SIZ markers, which are part of the TIFF file format specification used for image storage. The flaw manifests when the application fails to properly validate user-supplied data during the parsing process, creating a condition where memory access extends beyond the boundaries of allocated objects. This type of vulnerability falls under the CWE-125 category of "Out-of-bounds Read" which is classified as a memory safety error that can lead to information disclosure and potentially more severe exploitation opportunities.
The exploitation of this vulnerability requires user interaction through either visiting a malicious web page or opening a specially crafted malicious file, making it a client-side attack vector that leverages social engineering techniques. The technical implementation involves the application's handling of TIFF image files where the xTsiz member contains size information that is not properly validated before use. When an attacker crafts a malicious TIFF file with malformed SIZ markers, the parsing routine attempts to read memory locations beyond the intended buffer boundaries, potentially exposing sensitive data from adjacent memory regions. This read past the end of an allocated object can reveal confidential information such as stack contents, heap data, or other process memory that may contain authentication tokens, encryption keys, or other sensitive application data.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on Foxit Reader for document processing, as it can lead to unauthorized data disclosure that may compromise system security. The vulnerability's classification as a remote attack vector means that attackers can exploit it without requiring physical access to target systems, making it particularly dangerous in enterprise environments where document sharing is common. The fact that this vulnerability can be leveraged in conjunction with other exploits to achieve code execution in the context of the current process demonstrates how seemingly isolated memory safety issues can become stepping stones for more comprehensive attacks. This aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1068 for "Exploitation for Privilege Escalation" where initial information disclosure can enable subsequent attack phases.
Organizations should prioritize immediate patching of affected Foxit Reader installations to mitigate this vulnerability, as the ZDI-CAN-5013 identifier indicates that this issue was recognized and documented by the Zero Day Initiative. The recommended mitigation strategy involves updating to the latest version of Foxit Reader where proper input validation has been implemented for the SIZ marker parsing logic. Additionally, network administrators should consider implementing content filtering measures to prevent users from accessing potentially malicious TIFF files through web browsers or email attachments. Security monitoring should be enhanced to detect unusual file access patterns or memory read operations that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of robust input validation in document processing applications and highlights the need for comprehensive security testing of file format parsers to prevent similar issues from occurring in other software products.