CVE-2018-17670 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.2.0.9297. 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 handling of the content property of a XFA object. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-6524.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/05/2020
The vulnerability identified as CVE-2018-17670 represents a critical remote code execution flaw in Foxit Reader version 9.2.0.9297 that demonstrates the dangerous consequences of improper object validation in PDF processing applications. This vulnerability falls under the CWE-476 category of NULL Pointer Dereference, where the software fails to validate that an object exists before attempting operations on it. The flaw specifically manifests within the XFA (XML Forms Architecture) object handling mechanism, which is a sophisticated feature used for creating interactive forms within PDF documents. When Foxit Reader processes a maliciously crafted PDF containing an XFA object with a malformed content property, the application attempts to operate on a null or uninitialized object reference, creating a predictable execution path for attackers.
The exploitation of this vulnerability requires user interaction through either visiting a malicious webpage that hosts a crafted PDF or opening a maliciously prepared file, making it a typical client-side attack vector that aligns with ATT&CK technique T1203 - Exploitation for Client Execution. The attack chain begins when a user interacts with the malicious content, triggering the PDF parser to encounter the malformed XFA object. The absence of proper validation allows the application to proceed with operations on what should be a valid object reference, leading to memory corruption and ultimately arbitrary code execution. This type of vulnerability is particularly dangerous because it operates within the context of the currently running process, meaning the attacker can execute code with the same privileges as the Foxit Reader application, potentially compromising the entire system.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a fundamental breakdown in input validation and memory safety practices within the PDF processing engine. Attackers can leverage this flaw to install malware, steal sensitive information, or establish persistent access to affected systems. The vulnerability's presence in a widely used PDF reader application like Foxit Reader amplifies its potential impact, as it affects countless users who may encounter malicious PDFs through email attachments, web downloads, or other common attack vectors. The issue demonstrates how seemingly minor validation gaps in complex software can create significant security risks, particularly in applications that handle untrusted content such as PDF documents. Organizations using Foxit Reader are particularly vulnerable since the attack requires minimal user interaction and can be delivered through various attack channels.
Mitigation strategies for CVE-2018-17670 should focus on immediate patch application from Foxit Corporation, as this vulnerability was addressed in subsequent software updates. System administrators should implement defensive measures such as restricting PDF file execution in web browsers, implementing content filtering solutions, and monitoring for suspicious PDF file downloads or accesses. The vulnerability highlights the importance of robust input validation and defensive programming practices, particularly in applications that parse complex file formats. Organizations should also consider implementing sandboxing mechanisms for PDF processing and regularly updating all PDF reader software to ensure protection against known vulnerabilities. The incident serves as a reminder of the critical need for thorough security testing of file parsing components and the implementation of proper object validation techniques to prevent null pointer dereference conditions that can lead to remote code execution.