CVE-2021-31457
📋 TL;DR
This vulnerability in Foxit Reader allows remote attackers to execute arbitrary code by tricking users into opening malicious PDF files. The flaw exists in how Annotation objects are handled without proper validation, enabling code execution in the current process context. Users of affected Foxit Reader versions 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 user running Foxit Reader, potentially leading to data theft, ransomware deployment, or lateral movement.
Likely Case
Malicious code execution leading to malware installation, credential theft, or unauthorized access to sensitive documents.
If Mitigated
Limited impact with proper application sandboxing and user privilege restrictions, potentially containing the exploit to the application context.
🎯 Exploit Status
Exploit requires user interaction (opening malicious file). ZDI published advisory with technical details.
🛠️ 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 install latest version. 4. Restart computer after installation.
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
allPrevents JavaScript-based exploitation vectors
File > Preferences > JavaScript > Uncheck 'Enable JavaScript'
Use Protected View
allOpens files in restricted mode by default
File > Preferences > Trust Manager > Check 'Enable Safe Reading Mode'
🧯 If You Can't Patch
- Temporarily switch to alternative PDF readers like Adobe Reader or browser-based 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 10.1.1.37576 or earlier, system is vulnerable.Check Version:
On Windows: wmic product where name="Foxit Reader" get versionVerify Fix Applied:
Verify version is 10.1.2.37627 or later in Help > About.📡 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 to unknown IPs
- DNS requests for suspicious domains after PDF opening
SIEM Query:
process_name:"FoxitReader.exe" AND (event_id:1000 OR event_id:1001) AND exception_code:0xc0000005