CVE-2021-31449
📋 TL;DR
This vulnerability in Foxit Reader allows remote attackers to execute arbitrary code by tricking users into opening malicious PDF files containing specially crafted U3D objects. The flaw is a double-free vulnerability (CWE-415) that occurs when the software fails to validate object existence before performing free operations. Users of affected Foxit Reader versions are at risk.
💻 Affected Systems
- Foxit Reader
📦 What is this software?
Foxit Reader by Foxitsoftware
Phantompdf by Foxitsoftware
Phantompdf by Foxitsoftware
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through remote code execution, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Attacker gains code execution in the context of the current user, enabling credential theft, data exfiltration, or malware installation.
If Mitigated
Limited impact due to sandboxing, application hardening, or network segmentation preventing successful exploitation.
🎯 Exploit Status
Exploit requires user interaction (opening malicious PDF). ZDI published advisory with technical details. Weaponization likely due to RCE nature and available details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.1.2.37627 or later
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php
Restart Required: Yes
Instructions:
1. Download latest Foxit Reader from official website. 2. Run installer. 3. Restart system. 4. Verify version is 10.1.2.37627 or higher.
🔧 Temporary Workarounds
Disable U3D support
allPrevent rendering of U3D objects in PDF files
In Foxit Reader: Edit > Preferences > 3D & Multimedia > Uncheck 'Enable U3D content'
Use alternative PDF reader
allTemporarily switch to unaffected PDF reader software
🧯 If You Can't Patch
- Implement application whitelisting to block Foxit Reader execution
- Deploy network segmentation to limit lateral movement if compromised
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version: Help > About Foxit Reader. If version is 10.1.1.37576 or earlier, system is vulnerable.Check Version:
On Windows: wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Verify version is 10.1.2.37627 or later. Test opening PDFs with U3D content to ensure stability.📡 Detection & Monitoring
Log Indicators:
- Application crashes in Foxit Reader
- Unexpected process creation from Foxit Reader
- Memory access violations in application logs
Network Indicators:
- Outbound connections from Foxit Reader to unusual destinations
- DNS requests for known exploit domains
SIEM Query:
source="*foxit*" AND (event_id=1000 OR event_id=1001) OR process_name="foxitreader.exe" AND parent_process!="explorer.exe"