CVE-2018-9938 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit Reader 9.0.0.29935. 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 absPageSpan method. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to execute code under the context of the current process. Was ZDI-CAN-5372.
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Analysis
by VulDB Data Team • 07/14/2024
The vulnerability identified as CVE-2018-9938 represents a critical security flaw in Foxit Reader version 9.0.0.29935 that enables remote code execution through a type confusion vulnerability. This issue falls under the Common Weakness Enumeration category CWE-476 which specifically addresses NULL pointer dereferences and related memory corruption conditions. The vulnerability stems from insufficient input validation within the absPageSpan method implementation, creating a pathway for malicious actors to manipulate the application's memory handling processes. The flaw exists in the PDF rendering engine's object management system where user-supplied data is processed without adequate sanitization or type checking mechanisms.
Attackers can exploit this vulnerability by crafting malicious PDF files or web pages that contain specially formatted data structures designed to trigger the type confusion condition. The exploitation requires user interaction through either visiting a malicious web page or opening a crafted PDF document, making this a typical client-side attack vector. The type confusion occurs when the application incorrectly handles object type information during memory operations, allowing an attacker to manipulate the execution flow and potentially execute arbitrary code with the privileges of the currently running Foxit Reader process. This represents a significant risk since PDF readers are frequently used and often run with elevated privileges on user systems.
The operational impact of this vulnerability extends beyond simple code execution, as it can lead to complete system compromise when combined with other attack vectors or when users have administrative privileges. The vulnerability affects the core rendering functionality of Foxit Reader, meaning any document processing activity could potentially be exploited. From an adversarial perspective, this flaw aligns with ATT&CK technique T1203 which involves exploiting software vulnerabilities to gain unauthorized access. The vulnerability demonstrates how improper input validation can create persistent security risks that remain exploitable until patched, particularly in widely deployed applications like PDF readers that process untrusted content from various sources.
Organizations should implement immediate mitigations including disabling PDF preview features in web browsers, implementing strict content filtering for PDF documents, and ensuring all users have updated to patched versions of Foxit Reader. Security administrators should also consider network-based protections such as web application firewalls and intrusion detection systems that can identify and block malicious PDF content. The vulnerability highlights the importance of regular security updates and proper input validation in client-side applications, particularly those handling untrusted data from external sources. Additionally, user education regarding the risks of opening unknown PDF files and visiting untrusted websites remains crucial in reducing exploitation success rates.