CVE-2021-27261
📋 TL;DR
This vulnerability in Foxit PhantomPDF allows remote attackers to execute arbitrary code by tricking users into opening malicious PDF files containing specially crafted U3D objects. The flaw exists due to improper bounds checking when processing U3D data, leading to out-of-bounds memory reads that can be leveraged for code execution. Users of affected Foxit PhantomPDF versions are at risk.
💻 Affected Systems
- Foxit PhantomPDF
📦 What is this software?
Foxit Reader by Foxitsoftware
Phantompdf by Foxitsoftware
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution with user privileges, potentially leading to data theft, ransomware deployment, or lateral movement within networks.
Likely Case
Malicious actor gains code execution on victim's machine through phishing emails with malicious PDF attachments, enabling data exfiltration or malware installation.
If Mitigated
Attack fails due to patched software, security controls blocking malicious files, or user awareness preventing malicious PDF opening.
🎯 Exploit Status
Exploitation requires user to open malicious PDF but no authentication needed. Weaponization likely due to ZDI publication and RCE nature.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.1.1 or later
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php
Restart Required: Yes
Instructions:
1. Download latest Foxit PhantomPDF from official website. 2. Run installer. 3. Restart system. 4. Verify version is 10.1.1 or higher.
🔧 Temporary Workarounds
Disable U3D support
windowsDisable U3D object processing in Foxit PhantomPDF settings
Use alternative PDF viewer
allTemporarily use different PDF software until patched
🧯 If You Can't Patch
- Block PDF files at email gateways and web proxies
- Implement application whitelisting to prevent unauthorized executables
🔍 How to Verify
Check if Vulnerable:
Check Foxit PhantomPDF version in Help > About. If version is 10.1.0.37527 or earlier, system is vulnerable.Check Version:
wmic product where name="Foxit PhantomPDF" get versionVerify Fix Applied:
Verify version is 10.1.1 or higher in Help > About. Test with known safe PDF containing U3D objects.📡 Detection & Monitoring
Log Indicators:
- Foxit PhantomPDF crash logs with memory access violations
- Windows Event Logs showing application crashes with exception codes like 0xC0000005
Network Indicators:
- Unusual outbound connections from Foxit process after PDF opening
- PDF downloads from suspicious sources
SIEM Query:
source="windows" AND (event_id=1000 OR event_id=1001) AND process_name="FoxitPhantomPDF.exe" AND exception_code="0xC0000005"