CVE-2021-34950
📋 TL;DR
This vulnerability in Foxit PDF Reader allows remote attackers to execute arbitrary code by tricking users into opening malicious PDF files. The flaw exists in how Annotation objects are handled, enabling out-of-bounds reads that can lead to remote code execution. All users of affected Foxit PDF Reader versions are at risk.
💻 Affected Systems
- Foxit PDF Reader
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the victim's computer, 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 file access, credential theft, and installation of additional malware.
If Mitigated
Limited impact with proper security controls like application sandboxing, privilege separation, and network segmentation preventing lateral movement.
🎯 Exploit Status
Exploitation requires user interaction but no authentication. The vulnerability is well-documented and likely incorporated into exploit kits.
🛠️ 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. Open Foxit PDF Reader
2. Go to Help > Check for Updates
3. Follow prompts to update to version 11.1.0.52543 or later
4. Restart the application
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
windowsPrevents JavaScript-based exploitation vectors that might leverage this vulnerability
File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
windowsOpen PDFs in protected mode to limit potential damage
File > Preferences > General > Check 'Open documents in Protected View'
🧯 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: Help > About Foxit Reader. If version is below 11.1.0.52543, you are vulnerable.Check Version:
wmic product where "name like 'Foxit%Reader%'" get versionVerify Fix Applied:
Verify version is 11.1.0.52543 or higher in Help > About Foxit Reader.📡 Detection & Monitoring
Log Indicators:
- Foxit Reader crash logs with memory access violations
- Unexpected child processes spawned from Foxit Reader
- Network connections initiated by Foxit Reader process
Network Indicators:
- Downloads of PDF files from suspicious sources
- Outbound connections from Foxit Reader to unknown IPs
SIEM Query:
process_name:"FoxitReader.exe" AND (event_id:1000 OR event_id:1001) AND (exception_code:0xc0000005 OR exception_code:0xc0000409)