CVE-2021-31461
📋 TL;DR
This vulnerability in Foxit Reader allows remote attackers to execute arbitrary code by tricking users into opening malicious PDF files or visiting malicious web pages. The flaw exists in how the software handles app.media objects, leading to type confusion that can be exploited for code execution. All users running affected versions of Foxit Reader are at risk.
💻 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 with attacker gaining the same privileges as the current user, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Malware installation or data exfiltration from the compromised system, often through phishing campaigns delivering malicious PDF documents.
If Mitigated
Limited impact if executed in sandboxed environments or with restricted user privileges, though still potentially damaging to user data and local system integrity.
🎯 Exploit Status
Exploitation requires user interaction but no authentication. The vulnerability was discovered by Zero Day Initiative (ZDI-CAN-13333) and weaponization in targeted attacks is likely given the nature of PDF reader vulnerabilities.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.1.2.37627 and later
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php
Restart Required: Yes
Instructions:
1. Open Foxit Reader. 2. Go to Help > Check for Updates. 3. Follow prompts to download and install version 10.1.2.37627 or later. 4. Restart the application and system if prompted.
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
allPrevents exploitation by disabling JavaScript execution which is often used in PDF-based attacks
Open Foxit Reader > File > Preferences > Trust Manager > Uncheck 'Enable JavaScript'
Use Protected View
allOpen all PDFs in Protected View mode to limit potential damage
File > Preferences > Trust Manager > Check 'Enable Safe Reading Mode'
🧯 If You Can't Patch
- Use alternative PDF readers that are not affected by this vulnerability
- Implement application whitelisting to block execution of Foxit Reader
🔍 How to Verify
Check if Vulnerable:
Open Foxit Reader, go to Help > About Foxit Reader and check if version is 10.1.1.37576 or earlierCheck Version:
On Windows: wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Verify Foxit Reader version is 10.1.2.37627 or later in Help > About Foxit Reader📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from Foxit Reader
- Multiple failed JavaScript execution attempts in Foxit logs
- Unexpected network connections from Foxit Reader process
Network Indicators:
- Outbound connections to suspicious domains after PDF opening
- Unusual download patterns from Foxit Reader process
SIEM Query:
process_name:"FoxitReader.exe" AND (parent_process:explorer.exe OR cmdline:*javascript* OR network_connection:*)