CVE-2018-9959 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 pageNum document 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-5432.
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Analysis
by VulDB Data Team • 02/06/2020
CVE-2018-9959 represents a critical remote code execution vulnerability affecting Foxit Reader version 9.0.1.1049, demonstrating a classic improper input validation flaw that aligns with CWE-843. The vulnerability stems from inadequate validation during the parsing of the pageNum document attribute, where the software fails to verify object existence before performing operations on it. This fundamental flaw creates a dangerous condition where attacker-controlled input can trigger arbitrary code execution within the application's process context, effectively bypassing standard security boundaries and establishing a persistent threat vector. The vulnerability requires user interaction to exploit, meaning attackers must entice victims to visit malicious web pages or open compromised files, making it particularly dangerous in targeted attack scenarios.
The technical exploitation of this vulnerability occurs through a type of buffer manipulation attack that leverages the lack of proper object validation. When Foxit Reader processes a malicious PDF document containing crafted pageNum attributes, the application attempts to access memory locations without first confirming that the referenced objects exist within the document structure. This creates a scenario where attackers can manipulate memory pointers or object references to redirect execution flow, ultimately allowing code injection attacks. The vulnerability's classification as a remote code execution flaw indicates that attackers do not require physical access to the target system, making it particularly concerning for enterprise environments where users may inadvertently encounter malicious content through email attachments, web browsing, or document sharing platforms.
From an operational impact perspective, this vulnerability presents significant risk to organizations relying on Foxit Reader for document processing, as it enables attackers to gain full control over affected systems. The execution occurs under the privileges of the current process, meaning that if Foxit Reader is running with elevated permissions, attackers could potentially escalate their privileges further. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter), as it enables attackers to execute arbitrary commands through the vulnerable application interface. The attack chain typically involves crafting a malicious PDF document, delivering it to target users through various vectors, and leveraging the user's interaction to trigger the exploit, making it a prime candidate for social engineering campaigns.
Organizations should implement immediate mitigations including patching to the latest Foxit Reader versions that address this vulnerability, as well as network-based controls such as web application firewalls and content filtering solutions that can detect and block malicious PDF content. Security teams should also consider implementing user education programs to reduce the risk of successful social engineering attacks that exploit this vulnerability. Additionally, organizations should conduct vulnerability assessments to identify all systems running affected versions of Foxit Reader and implement process isolation techniques where possible. The vulnerability demonstrates the importance of proper input validation and object existence checking, principles that should be enforced across all document processing applications to prevent similar issues in the future. Continuous monitoring and incident response procedures should be enhanced to detect potential exploitation attempts, particularly in environments where PDF document handling is common.