CVE-2020-6146
📋 TL;DR
CVE-2020-6146 is a heap-based buffer overflow vulnerability in Nitro Pro PDF software that allows remote code execution when processing malicious PDF documents. Attackers can exploit this by tricking users into opening specially crafted PDF files, potentially taking full control of affected systems. This affects users of Nitro Pro versions 13.13.2.242 and 13.16.2.300.
💻 Affected Systems
- Nitro Pro
📦 What is this software?
Nitro Pro by Gonitro
Nitro Pro by Gonitro
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the victim's computer, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Malicious actor executes arbitrary code with the privileges of the user opening the PDF, leading to data exfiltration, credential theft, or lateral movement within the network.
If Mitigated
If proper controls like application whitelisting and least privilege are implemented, exploitation would be limited to the user's context with restricted impact.
🎯 Exploit Status
Exploitation requires user interaction to open malicious PDF but is technically straightforward once the document is loaded.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 13.16.2.300
Vendor Advisory: https://www.gonitro.com/nps/security/updates
Restart Required: Yes
Instructions:
1. Open Nitro Pro. 2. Go to Help > Check for Updates. 3. Follow prompts to install latest version. 4. Restart computer after installation.
🔧 Temporary Workarounds
Disable Nitro Pro as default PDF handler
windowsPrevent Nitro Pro from automatically opening PDF files to reduce attack surface.
Control Panel > Default Programs > Set Default Programs > Select different PDF reader
Block malicious PDFs at perimeter
allConfigure email/web gateways to block PDF files with suspicious characteristics.
🧯 If You Can't Patch
- Implement application whitelisting to prevent unauthorized executables from running
- Configure Windows Defender Exploit Guard or similar EDR solutions to detect heap corruption attempts
🔍 How to Verify
Check if Vulnerable:
Check Nitro Pro version via Help > About Nitro Pro. If version is exactly 13.13.2.242 or 13.16.2.300, system is vulnerable.Check Version:
wmic product where name="Nitro Pro" get versionVerify Fix Applied:
Verify Nitro Pro version is higher than 13.16.2.300 after update.📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs showing Nitro Pro crashes (Event ID 1000)
- Unexpected child processes spawned from nitro_pro.exe
Network Indicators:
- Outbound connections from Nitro Pro process to unknown IPs
- DNS requests for command and control domains
SIEM Query:
process_name="nitro_pro.exe" AND (event_id=1000 OR parent_process!="explorer.exe")