CVE-2021-31473
📋 TL;DR
CVE-2021-31473 is a remote code execution vulnerability in Foxit Reader's browseForDoc function. Attackers can exploit it by tricking users into opening malicious PDF files or visiting malicious web pages, allowing arbitrary code execution in the context of the current process. This affects users of vulnerable Foxit Reader versions.
💻 Affected Systems
- Foxit Reader
📦 What is this software?
Phantompdf by Foxitsoftware
Phantompdf by Foxitsoftware
Reader by Foxitsoftware
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through arbitrary code execution with the same privileges as the user running Foxit Reader, potentially leading to data theft, ransomware deployment, or lateral movement.
Likely Case
Malware installation, credential theft, or data exfiltration through crafted PDF documents or web pages.
If Mitigated
Limited impact if proper application sandboxing, least privilege principles, and network segmentation are implemented.
🎯 Exploit Status
Exploitation requires user interaction but is straightforward once malicious content is delivered. ZDI published advisory with technical details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.1.4.37651 and later
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php
Restart Required: Yes
Instructions:
1. Download latest Foxit Reader from official website. 2. Run installer. 3. Restart system if prompted. 4. Verify version is 10.1.4.37651 or higher.
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
allPrevents JavaScript-based exploitation vectors
Open Foxit Reader > File > Preferences > Trust Manager > Uncheck 'Enable JavaScript'
Use Protected View
allOpens documents in restricted mode
Open Foxit Reader > File > Preferences > Trust Manager > Check 'Safe Reading Mode'
🧯 If You Can't Patch
- Uninstall Foxit Reader and use alternative PDF viewers
- Implement application whitelisting to block Foxit Reader execution
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version in Help > About. If version is 10.1.3.37598 or earlier, system is vulnerable.Check Version:
On Windows: wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Verify version is 10.1.4.37651 or higher in Help > About.📡 Detection & Monitoring
Log Indicators:
- Process creation events from Foxit Reader with unusual command-line arguments
- Crash reports from Foxit Reader
Network Indicators:
- Downloads of PDF files from untrusted sources
- HTTP requests to suspicious domains following PDF opening
SIEM Query:
source="*foxit*" AND (event_type="process_creation" OR event_type="crash")