CVE-2023-51551
📋 TL;DR
This is a use-after-free vulnerability in Foxit PDF Reader's AcroForm signature handling that allows remote code execution. Attackers can exploit it by tricking users into opening malicious PDF files, potentially taking full control of affected systems. All users running vulnerable versions of Foxit PDF Reader are affected.
💻 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 current user, potentially leading to data theft, ransomware deployment, or lateral movement within networks.
Likely Case
Malicious code execution in the context of the current user, allowing data access, persistence mechanisms, and credential harvesting.
If Mitigated
Limited impact if proper application sandboxing, least privilege principles, and network segmentation are implemented.
🎯 Exploit Status
User interaction required (opening malicious PDF). The vulnerability is in the Zero Day Initiative database (ZDI-CAN-22003), suggesting active research interest.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2024.1 and 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 install version 2024.1 or later
4. Restart the application
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
allPrevents JavaScript-based exploitation vectors that might be used to trigger the vulnerability
File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
windowsOpen untrusted PDFs in protected/sandboxed mode
File > Preferences > Trust Manager > Check 'Enable Safe Reading Mode'
🧯 If You Can't Patch
- Use alternative PDF readers that are not vulnerable
- Implement application whitelisting to block Foxit Reader execution
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version in Help > About. If version is below 2024.1, the system is vulnerable.Check Version:
On Windows: wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Confirm version is 2024.1 or higher in Help > About.📡 Detection & Monitoring
Log Indicators:
- Unexpected Foxit Reader crashes
- Process creation from Foxit Reader with unusual command lines
- Network connections initiated by Foxit Reader
Network Indicators:
- Downloads of PDF files from untrusted sources
- HTTP requests from Foxit Reader to suspicious domains
SIEM Query:
process_name:"FoxitReader.exe" AND (event_id:1000 OR parent_process:!explorer.exe)