CVE-2021-47891
📋 TL;DR
CVE-2021-47891 is a critical remote code execution vulnerability in Unified Remote 3.9.0.2463 that allows attackers to send crafted network packets to execute arbitrary commands on affected systems. Attackers can exploit this by connecting to port 9512 and sending specially crafted packets to open command prompts and download/execute malicious payloads. This affects all users running the vulnerable version of Unified Remote.
💻 Affected Systems
- Unified Remote
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control, installing persistent backdoors, stealing sensitive data, and using the system as a pivot point for lateral movement.
Likely Case
Attackers execute arbitrary commands to install malware, cryptocurrency miners, ransomware, or create backdoors for persistent access.
If Mitigated
Limited impact with proper network segmentation and access controls preventing exploitation attempts.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB (ID 49587), making exploitation trivial for attackers with basic networking knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 3.9.0.2463
Vendor Advisory: https://www.unifiedremote.com/
Restart Required: Yes
Instructions:
1. Download the latest version from https://www.unifiedremote.com/download 2. Uninstall the current version 3. Install the updated version 4. Restart the system
🔧 Temporary Workarounds
Block Port 9512
allBlock inbound and outbound traffic on port 9512 using firewall rules
Windows: netsh advfirewall firewall add rule name="Block Unified Remote" dir=in action=block protocol=TCP localport=9512
Linux: sudo iptables -A INPUT -p tcp --dport 9512 -j DROP
Disable Unified Remote Service
allStop and disable the Unified Remote service to prevent exploitation
Windows: sc stop UnifiedRemote && sc config UnifiedRemote start= disabled
Linux: sudo systemctl stop unifiedremote && sudo systemctl disable unifiedremote
🧯 If You Can't Patch
- Implement strict network segmentation to isolate systems running Unified Remote
- Deploy host-based intrusion detection/prevention systems to monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check if Unified Remote version 3.9.0.2463 is installed and if port 9512 is listeningCheck Version:
Windows: wmic product where name="Unified Remote" get version | Linux: dpkg -l | grep unified-remote | macOS: pkgutil --pkgs | grep unifiedremoteVerify Fix Applied:
Verify Unified Remote version is updated beyond 3.9.0.2463 and port 9512 is properly secured or blocked📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from Unified Remote service
- Command prompt or PowerShell execution from Unified Remote process
- Network connections to suspicious external IPs from Unified Remote
Network Indicators:
- Unusual traffic patterns on port 9512
- Multiple connection attempts to port 9512 from single sources
- Large or malformed packets sent to port 9512
SIEM Query:
source="unifiedremote" AND (event_type="process_creation" OR dest_port=9512) AND (process_name="cmd.exe" OR process_name="powershell.exe" OR packet_size>1000)