CVE-2021-34970
📋 TL;DR
This is a format string vulnerability in Foxit PDF Reader's print method that allows information disclosure. Attackers can exploit it by tricking users into opening malicious PDF files or visiting malicious web pages. The vulnerability affects users of Foxit PDF Reader who open untrusted documents.
💻 Affected Systems
- Foxit PDF Reader
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could combine this information disclosure vulnerability with other exploits to achieve arbitrary code execution in the context of the current user, potentially leading to full system compromise.
Likely Case
Remote attackers disclose sensitive memory information from the Foxit PDF Reader process, which could include pointers, stack data, or other information useful for further exploitation.
If Mitigated
With proper controls, the impact is limited to information disclosure only, preventing escalation to code execution.
🎯 Exploit Status
Requires user interaction and likely needs to be combined with other vulnerabilities for full exploitation
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.0.1 and 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 update to version 11.0.1 or later
4. Restart the application
🔧 Temporary Workarounds
Disable JavaScript in Foxit Reader
windowsPrevents malicious PDFs from executing JavaScript that could trigger the vulnerability
1. Open Foxit Reader
2. Go to File > Preferences
3. Select JavaScript
4. Uncheck 'Enable JavaScript'
5. Click OK
Use Alternative PDF Reader
allTemporarily use a different PDF reader while waiting for patching
🧯 If You Can't Patch
- Restrict user permissions to limit potential damage from exploitation
- Implement application whitelisting to prevent unauthorized PDF readers
🔍 How to Verify
Check if Vulnerable:
Check Foxit Reader version: Open Foxit Reader > Help > About Foxit ReaderCheck Version:
Not applicable - check via GUI as describedVerify Fix Applied:
Verify version is 11.0.1 or higher in Help > About Foxit Reader📡 Detection & Monitoring
Log Indicators:
- Unusual Foxit Reader process crashes
- Multiple print method calls from single PDF
Network Indicators:
- Downloads of PDF files from untrusted sources
- Network connections initiated by Foxit Reader to suspicious domains
SIEM Query:
Process:foxitreader.exe AND (EventID:1000 OR EventID:1001) OR FileExtension:pdf AND SourceIP:(suspicious_ips)