CVE-2023-42094
📋 TL;DR
This CVE describes a use-after-free vulnerability in Foxit PDF Reader's annotation handling, allowing remote attackers to execute arbitrary code by tricking users into opening malicious PDF files. It affects users of vulnerable Foxit PDF Reader versions, requiring user interaction via visiting a malicious page or opening a file.
💻 Affected Systems
- Foxit PDF Reader
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining control over the user's system, leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Remote code execution in the context of the current user, potentially resulting in malware installation, credential harvesting, or unauthorized access to local files.
If Mitigated
Limited impact if patched or with strict controls, such as blocking untrusted PDFs, reducing the attack surface to minimal or no exploitation.
🎯 Exploit Status
Exploitation requires user interaction but leverages a common vulnerability type (use-after-free) that is often weaponized in attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Foxit security bulletins for specific patched versions.
Vendor Advisory: https://www.foxit.com/support/security-bulletins.html
Restart Required: Yes
Instructions:
1. Visit Foxit's security bulletins page. 2. Download and install the latest patched version of Foxit PDF Reader. 3. Restart the application or system as prompted.
🔧 Temporary Workarounds
Disable PDF Reader in Browser
allPrevent automatic opening of PDFs in Foxit Reader via web browsers to reduce attack surface.
In browser settings, change PDF handling to use a different viewer or download only.
Use Alternative PDF Viewer
allTemporarily switch to a non-vulnerable PDF reader until patched.
Install and set as default a secure PDF viewer like Adobe Acrobat Reader or browser built-in viewers.
🧯 If You Can't Patch
- Implement application whitelisting to block execution of Foxit PDF Reader from untrusted locations.
- Enhance user awareness training to avoid opening PDFs from unknown or suspicious sources.
🔍 How to Verify
Check if Vulnerable:
Check the installed version of Foxit PDF Reader against the patched versions listed in Foxit's security bulletins.Check Version:
On Windows: Open Foxit PDF Reader, go to Help > About Foxit Reader. On macOS: Open the app, go to Foxit Reader > About Foxit Reader.Verify Fix Applied:
Confirm the version is updated to a patched release by checking the application's about or help menu.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from Foxit Reader, crash logs related to annotation handling, or unexpected network connections post-PDF opening.
Network Indicators:
- Outbound connections to suspicious IPs or domains after opening a PDF file.
SIEM Query:
Example: event_id=4688 AND process_name='FoxitReader.exe' AND parent_process_name='explorer.exe' AND command_line LIKE '%.pdf%'