CVE-2023-27379
📋 TL;DR
A use-after-free vulnerability in Foxit PDF Reader's JavaScript engine allows arbitrary code execution when users open malicious PDF files or visit malicious websites with the browser plugin enabled. This affects Foxit PDF Reader version 12.1.2.15332 users who open untrusted PDF documents or browse untrusted websites with the browser extension active.
💻 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, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Malware installation leading to credential theft, data exfiltration, or system disruption through drive-by download attacks via malicious websites.
If Mitigated
Limited impact with proper controls - potential application crash but no code execution if memory protections are enabled.
🎯 Exploit Status
Exploitation requires user interaction (opening file or visiting site) but no authentication. Memory corruption exploitation requires specific heap grooming.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 12.1.3 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 install latest version 4. Restart computer after installation
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
allPrevents exploitation by disabling JavaScript engine where vulnerability exists
Open Foxit Reader > File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Disable Browser Plugin
allPrevents web-based exploitation via malicious websites
Open browser extensions/settings and disable Foxit PDF Reader plugin
🧯 If You Can't Patch
- Restrict PDF file opening to trusted sources only using application whitelisting
- Implement network segmentation to limit lateral movement if exploitation occurs
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version: Open Foxit > Help > About Foxit ReaderCheck Version:
On Windows: wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Verify version is 12.1.3 or higher in About dialog📡 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_name:"FoxitReader.exe" AND (event_id:1000 OR parent_process_name:"FoxitReader.exe")