CVE-2020-14425: Foxit Reader RCE Vulnerability

CVE-2020-14425 Overview

CVE-2020-14425 is a Remote Command Execution vulnerability affecting Foxit Reader versions prior to 10.0. The vulnerability exists in the app.openCPDFWebPage JavaScript API, which allows attackers to execute local files and bypass security dialogs. When a user opens a maliciously crafted PDF document, an attacker can leverage this API to execute arbitrary commands on the victim's system without proper authorization checks.

Critical Impact

Attackers can achieve remote command execution by distributing malicious PDF documents that exploit the app.openCPDFWebPage JavaScript API, potentially leading to complete system compromise when users open the weaponized files.

Affected Products

• Foxit Reader versions prior to 10.0
• All platforms running vulnerable Foxit Reader versions

Discovery Timeline

• 2020-11-02 - CVE-2020-14425 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-14425

Vulnerability Analysis

This vulnerability stems from improper validation within the app.openCPDFWebPage JavaScript API implemented in Foxit Reader. The API fails to properly restrict its capabilities, allowing attackers to reference and execute local files on the victim's system. Critically, the vulnerability enables bypassing security dialogs that would normally warn users about potentially dangerous operations.

The attack requires user interaction—specifically, the victim must open a maliciously crafted PDF document. Once opened, the embedded JavaScript code executes within the context of Foxit Reader, leveraging the vulnerable API to perform unauthorized actions. Given the local attack vector with no privileges required beyond user interaction, successful exploitation can result in full compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of CVE-2020-14425 lies in insufficient security controls around the app.openCPDFWebPage JavaScript API. The API implementation lacks proper validation of the resources it can access, allowing it to reference local file paths. Additionally, the security dialog bypass indicates missing or improperly implemented user consent mechanisms that should prevent automated execution of sensitive operations.

Attack Vector

The attack is executed locally through a malicious PDF document. The attack chain proceeds as follows:

1. Distribution: An attacker creates a weaponized PDF document containing malicious JavaScript code that leverages the app.openCPDFWebPage API
2. Delivery: The malicious PDF is delivered to the victim through email attachments, malicious downloads, or compromised websites
3. Execution: When the victim opens the PDF in a vulnerable Foxit Reader version, the embedded JavaScript executes automatically
4. Exploitation: The JavaScript code calls the app.openCPDFWebPage API with crafted parameters to execute local files
5. Security Bypass: The vulnerability allows bypassing security dialogs, enabling the attack to proceed without user awareness

Technical details and proof-of-concept code are available in the Exploit-DB entry #48982 and the Packet Storm Security report.

Detection Methods for CVE-2020-14425

Indicators of Compromise

• PDF files containing JavaScript code that references the app.openCPDFWebPage API with suspicious parameters
• Foxit Reader processes spawning unexpected child processes or executing local files
• Unusual process execution chains originating from FoxitReader.exe
• JavaScript execution within PDF documents attempting to access local file system resources

Detection Strategies

• Deploy endpoint detection rules to monitor for Foxit Reader spawning suspicious child processes
• Implement file analysis solutions to scan incoming PDF documents for malicious JavaScript patterns
• Configure SIEM rules to alert on process execution anomalies where FoxitReader.exe is the parent process
• Use behavioral analysis to detect PDF documents attempting to bypass security dialogs

Monitoring Recommendations

• Enable enhanced logging for Foxit Reader application events and JavaScript execution
• Monitor network endpoints for distribution of malicious PDF documents via email or web downloads
• Implement real-time alerting for any Foxit Reader instances executing commands or accessing sensitive system resources
• Track installed Foxit Reader versions across the environment to identify vulnerable installations

How to Mitigate CVE-2020-14425

Immediate Actions Required

• Update Foxit Reader to version 10.0 or later immediately across all systems
• Disable JavaScript execution in Foxit Reader as a temporary mitigation if immediate patching is not possible
• Block or quarantine PDF attachments from untrusted sources until systems are patched
• Alert users about the risks of opening PDF documents from unknown sources

Patch Information

Foxit Software has addressed this vulnerability in Foxit Reader version 10.0. Organizations should upgrade all Foxit Reader installations to version 10.0 or later. The official security bulletin and patch information is available at the Foxit Software Security Bulletin.

Workarounds

• Disable JavaScript execution in Foxit Reader via Preferences > JavaScript > uncheck "Enable JavaScript Actions"
• Use Safe Reading Mode in Foxit Reader to prevent automatic execution of potentially malicious content
• Consider using alternative PDF readers until patching is complete
• Implement application whitelisting to prevent Foxit Reader from executing unauthorized processes

To disable JavaScript in Foxit Reader, navigate to the preferences menu:

Foxit Reader > Edit > Preferences > JavaScript
Uncheck "Enable JavaScript Actions"
Click OK to save settings