CVE-2021-38567
📋 TL;DR
This vulnerability in Foxit PDF software on macOS allows attackers to cause a crash via NULL pointer dereference by exploiting mishandled missing dictionary entries in PDF files. It affects users of Foxit PDF Editor and PDF Reader on macOS before version 11.0.1. The issue could potentially lead to denial of service or be leveraged for further exploitation.
💻 Affected Systems
- Foxit PDF Editor
- Foxit PDF Reader
📦 What is this software?
Pdf Editor by Foxitsoftware
⚠️ Risk & Real-World Impact
Worst Case
Application crash leading to denial of service, potential memory corruption that could be leveraged for arbitrary code execution if combined with other vulnerabilities.
Likely Case
Application crash when processing malicious PDF files, causing denial of service and potential data loss from unsaved work.
If Mitigated
Application crash with no further impact if proper sandboxing and memory protections are in place.
🎯 Exploit Status
Requires user to open a malicious PDF file. No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.0.1
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php
Restart Required: Yes
Instructions:
1. Open Foxit PDF Editor/Reader. 2. Go to Help > Check for Updates. 3. Follow prompts to update to version 11.0.1 or later. 4. Restart the application after update completes.
🔧 Temporary Workarounds
Disable PDF opening in Foxit
macOSChange default PDF handler to another application to prevent automatic opening in vulnerable Foxit versions
Right-click any PDF file > Get Info > Open with > Select alternative PDF reader > Change All
Restrict PDF file sources
allImplement policies to only allow PDFs from trusted sources
🧯 If You Can't Patch
- Use alternative PDF software for opening untrusted PDF files
- Implement application whitelisting to block execution of vulnerable Foxit versions
🔍 How to Verify
Check if Vulnerable:
Check Foxit version: Open Foxit > Help > About Foxit PDF Editor/Reader. If version is below 11.0.1, system is vulnerable.Check Version:
Open Foxit application and navigate to Help > About Foxit PDF Editor/ReaderVerify Fix Applied:
Verify version is 11.0.1 or higher in About dialog. Test opening various PDF files to ensure stability.📡 Detection & Monitoring
Log Indicators:
- Application crash logs from Foxit processes
- Error messages related to NULL pointer dereference
- Unexpected termination of Foxit processes
Network Indicators:
- Unusual PDF file downloads followed by application crashes
SIEM Query:
source="*foxit*" AND (event_type="crash" OR error="*NULL*" OR error="*dereference*")