CVE-2023-51556
📋 TL;DR
This vulnerability in Foxit PDF Reader allows attackers to execute arbitrary code by tricking users into opening malicious PDF files. It affects users running vulnerable versions of Foxit PDF Reader who open untrusted PDF documents. The flaw is a use-after-free issue in AcroForm Doc object handling.
💻 Affected Systems
- Foxit PDF Reader
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining the same privileges as the PDF Reader process, potentially leading to data theft, ransomware deployment, or lateral movement.
Likely Case
Malware installation or data exfiltration from the affected system when users open malicious PDFs from phishing emails or compromised websites.
If Mitigated
Limited impact with proper application sandboxing and user privilege restrictions, potentially containing the exploit to the PDF Reader process.
🎯 Exploit Status
Exploitation requires user interaction but no authentication. ZDI has published technical details but no public exploit code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2024.1 or later
Vendor Advisory: https://www.foxit.com/support/security-bulletins.html
Restart Required: Yes
Instructions:
1. Open Foxit PDF Reader
2. Go to Help > Check for Updates
3. Follow prompts to update to version 2024.1 or later
4. Restart the application
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
windowsPrevents JavaScript-based exploitation vectors
File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
windowsOpen untrusted PDFs in sandboxed Protected View mode
File > Preferences > Trust Manager > Check 'Enable Safe Reading Mode'
🧯 If You Can't Patch
- Switch to alternative PDF reader software temporarily
- Block PDF file downloads from untrusted sources via web proxy or email filtering
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version in Help > About. If version is below 2024.1, system is vulnerable.Check Version:
Not applicable - check via GUI in Help > AboutVerify Fix Applied:
Verify version is 2024.1 or higher in Help > About.📡 Detection & Monitoring
Log Indicators:
- Foxit Reader crash logs with memory access violations
- Unexpected child processes spawned from Foxit Reader
Network Indicators:
- Outbound connections from Foxit Reader process to unknown IPs
- DNS requests for suspicious domains after PDF opening
SIEM Query:
Process Creation where Parent Process Name contains 'FoxitReader.exe' AND Command Line contains unusual parameters