CVE-2023-47257
📋 TL;DR
This vulnerability in ConnectWise ScreenConnect allows man-in-the-middle attackers to send crafted messages that can lead to remote code execution. It affects all ScreenConnect installations up to version 23.8.4. Organizations using vulnerable versions for remote support or access are at risk.
💻 Affected Systems
- ConnectWise ScreenConnect
📦 What is this software?
Automate by Connectwise
Screenconnect by Connectwise
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining complete control over the ScreenConnect server, potentially leading to lateral movement across the network and data exfiltration.
Likely Case
Attackers intercepting communications between ScreenConnect clients and servers to execute arbitrary code on the server, enabling persistence and further exploitation.
If Mitigated
Limited impact with proper network segmentation, TLS enforcement, and monitoring preventing successful man-in-the-middle attacks.
🎯 Exploit Status
Exploitation requires man-in-the-middle position but no authentication. Public proof-of-concept code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 23.8.5 and later
Vendor Advisory: https://www.connectwise.com/company/trust/security-bulletins/connectwise-screenconnect-23.8-security-fix
Restart Required: Yes
Instructions:
1. Download ScreenConnect 23.8.5 or later from ConnectWise portal. 2. Backup current installation. 3. Run installer with administrative privileges. 4. Restart ScreenConnect services.
🔧 Temporary Workarounds
Enforce TLS 1.2+ Only
allConfigure ScreenConnect to only accept TLS 1.2 or higher connections to prevent downgrade attacks
Edit ScreenConnect web.config to set minimum TLS version
Network Segmentation
allIsolate ScreenConnect servers in dedicated network segments with strict firewall rules
🧯 If You Can't Patch
- Implement strict network monitoring for abnormal ScreenConnect traffic patterns
- Deploy intrusion detection systems to alert on man-in-the-middle attack indicators
🔍 How to Verify
Check if Vulnerable:
Check ScreenConnect version in web interface under Help > About. If version is 23.8.4 or earlier, system is vulnerable.Check Version:
On Windows: sc query ScreenConnect | findstr DisplayName. On Linux: systemctl status screenconnectVerify Fix Applied:
Verify version shows 23.8.5 or later in Help > About. Test connectivity to confirm services are running properly.📡 Detection & Monitoring
Log Indicators:
- Unusual authentication patterns
- Abnormal process creation from ScreenConnect service
- Error logs showing malformed message handling
Network Indicators:
- Unexpected TLS negotiation failures
- Abnormal traffic patterns between ScreenConnect clients and servers
- DNS spoofing attempts
SIEM Query:
source="ScreenConnect" AND (event_type="error" OR process_name="powershell.exe" OR cmdline="*powershell*")🔗 References
- https://web.archive.org/web/20240208140218/https://gotham-security.com/screenconnect-cve-2023-47256
- https://www.connectwise.com/company/trust/security-bulletins/connectwise-screenconnect-23.8-security-fix
- https://web.archive.org/web/20240208140218/https://gotham-security.com/screenconnect-cve-2023-47256
- https://www.connectwise.com/company/trust/security-bulletins/connectwise-screenconnect-23.8-security-fix
