CVE-2021-34962
📋 TL;DR
This is a use-after-free vulnerability in Foxit PDF Editor's handling of Caret Annotation objects that allows remote code execution. Attackers can exploit it by tricking users into opening malicious PDF files, potentially compromising affected systems. Users of vulnerable Foxit PDF Editor versions are at risk.
💻 Affected Systems
- Foxit PDF Editor
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining the same privileges as the current user, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local privilege escalation or arbitrary code execution in the context of the current user, allowing file access, credential theft, and persistence mechanisms.
If Mitigated
Limited impact due to sandboxing, application whitelisting, or restricted user privileges preventing full system compromise.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious PDF) but the vulnerability is well-documented and similar use-after-free vulnerabilities are commonly weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.1.0.52543 and later
Vendor Advisory: https://www.foxit.com/support/security-bulletins.html
Restart Required: Yes
Instructions:
1. Download latest version from Foxit website. 2. Run installer. 3. Restart system. 4. Verify version is 11.1.0.52543 or higher.
🔧 Temporary Workarounds
Disable PDF handling in Foxit
windowsChange default PDF handler to alternative application
Control Panel > Default Programs > Set Default Programs > Choose alternative PDF reader
Application Control Policy
windowsRestrict execution of Foxit PDF Editor via application whitelisting
🧯 If You Can't Patch
- Implement application sandboxing to limit potential damage from exploitation
- Use endpoint detection and response (EDR) to monitor for suspicious PDF-related process activity
🔍 How to Verify
Check if Vulnerable:
Open Foxit PDF Editor, go to Help > About and check version numberCheck Version:
Not applicable - check via GUI in Help > AboutVerify Fix Applied:
Confirm version is 11.1.0.52543 or higher in Help > About📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from FoxitPDFEditor.exe
- Memory access violations in application logs
- Multiple PDF file openings from untrusted sources
Network Indicators:
- Downloads of PDF files from suspicious domains
- Outbound connections from Foxit processes to unknown IPs
SIEM Query:
Process Creation where Image contains 'FoxitPDFEditor' AND ParentImage contains 'explorer' AND CommandLine contains '.pdf'