CVE-2018-9961 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.1.1049. 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 rect Field attribute. 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 under the context of the current process. Was ZDI-CAN-5434.
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Analysis
by VulDB Data Team • 02/06/2020
CVE-2018-9961 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.0.1.1049, classified under CWE-476 as NULL Pointer Dereference, which falls within the broader category of memory safety issues. This vulnerability operates through a classic object validation flaw where the PDF parser fails to verify whether a referenced object exists before attempting to access its properties. The specific weakness occurs during the parsing of the rect Field attribute, which is commonly used in PDF documents to define rectangular regions for various graphical elements. When processing maliciously crafted PDF files, the parser encounters a scenario where it attempts to dereference a null pointer, leading to unpredictable behavior and potential code execution. The vulnerability requires user interaction to be exploited, meaning that a victim must either visit a malicious webpage hosting the exploit or open a specially crafted PDF file containing the malicious payload. This attack vector aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and demonstrates the typical attack pattern where social engineering plays a crucial role in successful exploitation. The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary code with the privileges of the current user process, potentially leading to full system compromise. The vulnerability's exploitation mechanism operates at the application layer, targeting the PDF rendering engine's object handling capabilities and represents a significant risk to organizations relying on Foxit Reader for document processing. This flaw exemplifies the dangerous consequences of insufficient input validation and improper error handling in document parsing libraries, where a single missing validation check can provide attackers with a complete backdoor into the victim's system. Organizations should prioritize immediate remediation through official patches provided by Foxit Corporation, while implementing additional security controls such as web application firewalls and email filtering to prevent users from accessing malicious content. The vulnerability also underscores the importance of maintaining up-to-date security patches and demonstrates how seemingly minor parsing errors can have catastrophic security implications in widely-used software applications. Security professionals should monitor for exploitation attempts and consider implementing sandboxing techniques to limit the potential damage from successful exploitation attempts, while also ensuring that users are educated about the risks of opening untrusted PDF documents. This vulnerability serves as a reminder of the critical need for robust input validation and defensive programming practices in software development, particularly in applications that process untrusted data from external sources.