CVE-2021-34968
📋 TL;DR
This is a use-after-free vulnerability in Foxit PDF Editor's transitionToState method that allows remote attackers to execute arbitrary code. Attackers can exploit it by tricking users into opening malicious PDF files or visiting malicious web pages. All users running vulnerable versions of Foxit PDF Editor are affected.
💻 Affected Systems
- Foxit PDF Editor
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the victim's computer, enabling data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Malicious code execution in the context of the current user, potentially leading to credential theft, data exfiltration, or installation of persistent malware.
If Mitigated
Limited impact with proper sandboxing and application hardening, potentially contained to the PDF editor process only.
🎯 Exploit Status
Exploitation requires user interaction but has been weaponized by threat actors. The vulnerability is in the Zero Day Initiative database (ZDI-21-1199).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.0.1 and later
Vendor Advisory: https://www.foxit.com/support/security-bulletins.html
Restart Required: Yes
Instructions:
1. Download Foxit PDF Editor version 11.0.1 or later from official Foxit website. 2. Run the installer. 3. Follow installation prompts. 4. Restart computer after installation completes.
🔧 Temporary Workarounds
Disable JavaScript in Foxit PDF Editor
windowsPrevents exploitation by disabling JavaScript execution which is often used in PDF-based attacks
Open Foxit PDF Editor > File > Preferences > Security > Uncheck 'Enable JavaScript'
Use alternative PDF viewer
allTemporarily use a different PDF reader while waiting to patch
🧯 If You Can't Patch
- Implement application whitelisting to block execution of unauthorized PDF files
- Deploy network segmentation to isolate PDF processing workstations from critical systems
🔍 How to Verify
Check if Vulnerable:
Open Foxit PDF Editor > Help > About Foxit PDF Editor and check if version is below 11.0.1Check Version:
Not applicable - check via GUI in Help > About menuVerify Fix Applied:
Verify installed version is 11.0.1 or higher in Help > About Foxit PDF Editor📡 Detection & Monitoring
Log Indicators:
- Unexpected Foxit PDF Editor crashes
- Process creation from Foxit PDF Editor
- Network connections initiated by Foxit PDF Editor
Network Indicators:
- Outbound connections from Foxit PDF Editor to unknown IPs
- DNS requests for suspicious domains from PDF processing systems
SIEM Query:
process_name:"FoxitPDFEditor.exe" AND (event_type:crash OR parent_process:unusual OR network_connection:external)