CVE-2021-34966
📋 TL;DR
This is a use-after-free vulnerability in Foxit PDF Editor's handling of FileAttachment annotations 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 malware installation on the victim's machine, with potential for data exfiltration or persistence mechanisms.
If Mitigated
Limited impact due to sandboxing or application hardening, potentially resulting in application crash rather than code execution.
🎯 Exploit Status
User interaction required (opening malicious PDF). The vulnerability was discovered by Zero Day Initiative and has been publicly disclosed, increasing likelihood of exploitation.
🛠️ 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 if prompted. 4. Verify version is 11.1.0.52543 or higher.
🔧 Temporary Workarounds
Disable JavaScript in Foxit PDF Editor
windowsPrevents JavaScript-based exploitation vectors that might be used in conjunction with this vulnerability
Open Foxit PDF Editor > File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use alternative PDF viewer
allTemporarily use a different PDF application while patching
🧯 If You Can't Patch
- Implement application whitelisting to prevent execution of unauthorized PDF files
- Deploy network segmentation to limit lateral movement if exploitation occurs
🔍 How to Verify
Check if Vulnerable:
Check Foxit PDF Editor version in Help > About. If version is below 11.1.0.52543, system is vulnerable.Check Version:
Not applicable - check via GUI in Help > AboutVerify Fix Applied:
Verify version is 11.1.0.52543 or higher in Help > About dialog.📡 Detection & Monitoring
Log Indicators:
- Application crashes of Foxit PDF Editor
- Unusual process creation from Foxit processes
- Suspicious file access patterns
Network Indicators:
- Unexpected outbound connections from Foxit processes
- Downloads of PDF files from untrusted sources
SIEM Query:
Process creation where parent process contains 'foxit' AND (command line contains '.pdf' OR file path contains '.pdf')