CVE-2024-7725: Foxit PDF Editor RCE Vulnerability

CVE-2024-7725 Overview

CVE-2024-7725 is a Use-After-Free vulnerability affecting Foxit PDF Reader and Foxit PDF Editor that enables remote code execution. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader. 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 AcroForms. 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. This vulnerability was tracked as ZDI-CAN-23928.

Critical Impact

Successful exploitation allows attackers to execute arbitrary code in the context of the current process, potentially leading to complete system compromise, data theft, or lateral movement within an enterprise network.

Affected Products

• Foxit PDF Reader (all platforms)
• Foxit PDF Editor for Windows
• Foxit PDF Editor for Windows (multiple version branches)

Discovery Timeline

• 2024-08-21 - CVE-2024-7725 published to NVD
• 2024-10-18 - Last updated in NVD database

Technical Details for CVE-2024-7725

Vulnerability Analysis

This Use-After-Free vulnerability (CWE-416) occurs in the AcroForm handling component of Foxit PDF Reader and PDF Editor. The flaw stems from improper memory management where the application fails to validate whether an object still exists before performing operations on it. When a PDF document containing specially crafted AcroForm elements is processed, the application may reference memory that has already been freed, leading to memory corruption.

The network-based attack vector requires user interaction—specifically, the victim must open a malicious PDF file or visit a website hosting the malicious content. Once triggered, the vulnerability allows arbitrary code execution within the context of the current user's process, giving attackers the same privileges as the logged-in user.

Root Cause

The root cause of CVE-2024-7725 is insufficient validation in the AcroForm processing code. When handling AcroForm objects within PDF documents, the application does not properly verify that an object reference is still valid before attempting to use it. This creates a Use-After-Free condition where:

1. An AcroForm object is allocated in memory
2. The object is freed during processing
3. The application subsequently attempts to access the freed memory
4. Attackers can manipulate this freed memory to achieve code execution

Attack Vector

The attack requires crafting a malicious PDF document containing specially manipulated AcroForm elements designed to trigger the Use-After-Free condition. The attack flow typically involves:

1. Delivery: The attacker delivers the malicious PDF via email attachment, download link, or embedded in a web page
2. User Interaction: The victim opens the PDF file with a vulnerable version of Foxit PDF Reader or PDF Editor
3. Trigger: The malicious AcroForm elements cause the application to free an object and subsequently reference the freed memory
4. Exploitation: The attacker leverages heap manipulation techniques to control the freed memory contents, allowing arbitrary code execution

Since no verified code examples are available, technical details can be found in the Zero Day Initiative Advisory ZDI-24-1127.

Detection Methods for CVE-2024-7725

Indicators of Compromise

• Unexpected crashes or abnormal behavior in Foxit PDF Reader or PDF Editor when opening PDF files
• PDF files with unusually complex or nested AcroForm structures
• Process memory anomalies indicating heap corruption or code injection
• Suspicious child processes spawned from Foxit PDF Reader or PDF Editor

Detection Strategies

• Monitor for Foxit PDF Reader processes exhibiting unexpected behavior such as spawning child processes or making unusual network connections
• Implement endpoint detection rules to identify Use-After-Free exploitation patterns in memory
• Deploy file analysis capabilities to scan incoming PDF documents for malicious AcroForm structures
• Use SentinelOne's behavioral AI to detect post-exploitation activities following PDF document opening

Monitoring Recommendations

• Enable detailed logging for PDF application activity on endpoints
• Monitor email gateways and web proxies for PDF attachments from untrusted sources
• Implement application allowlisting to prevent unauthorized code execution from PDF reader processes
• Configure SentinelOne agents to monitor Foxit PDF applications for anomalous behavior

How to Mitigate CVE-2024-7725

Immediate Actions Required

• Update Foxit PDF Reader and Foxit PDF Editor to the latest patched versions immediately
• Enable Safe Reading Mode in Foxit PDF applications to disable JavaScript and prevent automatic execution of potentially dangerous content
• Implement network segmentation to limit the impact of potential compromises
• Educate users about the risks of opening PDF files from untrusted sources

Patch Information

Foxit has released security updates to address this vulnerability. Organizations should consult the Foxit Security Bulletin for specific version information and download links. Apply the latest available patches for both Foxit PDF Reader and Foxit PDF Editor across all affected systems.

Workarounds

• Enable Safe Reading Mode in Foxit PDF Reader/Editor: Navigate to File > Preferences > Trust Manager and enable "Enable Safe Reading Mode"
• Disable JavaScript execution in Foxit applications: Go to Edit > Preferences > JavaScript and uncheck "Enable JavaScript Actions"
• Use alternative PDF readers for opening untrusted documents until patches can be applied
• Implement strict email filtering to quarantine PDF attachments from external sources for manual review

# Configuration example - Registry settings to enable Safe Reading Mode (Windows)
# For Foxit PDF Reader
reg add "HKCU\Software\Foxit Software\Foxit Reader\Preferences\Security" /v SafeReading /t REG_DWORD /d 1 /f

# Disable JavaScript in Foxit PDF Reader
reg add "HKCU\Software\Foxit Software\Foxit Reader\Preferences\JavaScript" /v EnableJavaScript /t REG_DWORD /d 0 /f