CVE-2021-38098
📋 TL;DR
CVE-2021-38098 is a heap corruption vulnerability in Corel PDF Fusion 2.6.2.0 that allows arbitrary code execution when a user opens a malicious PDF file. Attackers can exploit this to run code with the victim's user privileges, requiring user interaction through file opening. This affects all users of the vulnerable software version.
💻 Affected Systems
- Corel PDF Fusion
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the victim's machine, data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Malware installation leading to data exfiltration, credential theft, or system disruption for individual users who open malicious PDFs.
If Mitigated
Limited impact with proper security controls preventing malicious PDFs from reaching users or sandboxing limiting damage scope.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious PDF) but no authentication. Heap corruption vulnerabilities typically require some exploit development skill.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to latest version (check Corel website for specific patched version)
Vendor Advisory: https://www.corel.com/security/
Restart Required: Yes
Instructions:
1. Open Corel PDF Fusion. 2. Navigate to Help > Check for Updates. 3. Follow prompts to download and install latest version. 4. Restart the application and system if prompted.
🔧 Temporary Workarounds
Disable PDF file association
windowsPrevent Corel PDF Fusion from automatically opening PDF files
Control Panel > Default Programs > Set Associations > Find .pdf > Change to different PDF reader
Application sandboxing
windowsRun Corel PDF Fusion in restricted environment
🧯 If You Can't Patch
- Block PDF files at network perimeter and email gateways
- Implement application allowlisting to prevent unauthorized execution
🔍 How to Verify
Check if Vulnerable:
Check Help > About in Corel PDF Fusion for version numberCheck Version:
Not applicable - check via application GUIVerify Fix Applied:
Verify version is updated beyond 2.6.2.0 and test with known safe PDF files📡 Detection & Monitoring
Log Indicators:
- Application crashes of Corel PDF Fusion
- Unusual process creation from PDF Fusion executable
Network Indicators:
- Downloads of PDF files from untrusted sources
- Outbound connections after PDF file opening
SIEM Query:
Process Creation where Image contains 'PDFFusion' AND ParentImage contains 'explorer'🔗 References
- https://www.fortiguard.com/zeroday/FG-VD-21-027
- https://www.fortinet.com/blog/threat-research/fortinet-security-researcher-discovers-multiple-vulnerabilities-across-multiple-corel-products
- https://www.fortiguard.com/zeroday/FG-VD-21-027
- https://www.fortinet.com/blog/threat-research/fortinet-security-researcher-discovers-multiple-vulnerabilities-across-multiple-corel-products
