CVE-2025-56234
📋 TL;DR
The AT_NA2000 PLC from Nanda Automation Technology has a TCP implementation flaw that violates RFC5961 by accepting RST packets with sequence numbers anywhere within the receive window, not just the exact expected value. This allows attackers to disrupt TCP connections by sending multiple random RST packets, causing denial-of-service. Organizations using AT_NA2000 PLCs in industrial control systems are affected.
💻 Affected Systems
- AT_NA2000 PLC
⚠️ 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
Critical industrial processes could be disrupted, causing production downtime, equipment damage, or safety incidents if PLCs controlling machinery lose network connectivity.
Likely Case
Intermittent network connectivity issues affecting PLC communications, leading to operational disruptions and potential data loss in industrial environments.
If Mitigated
Minimal impact with proper network segmentation and monitoring, though PLCs remain vulnerable to targeted attacks within the network.
🎯 Exploit Status
Exploitation requires network access to the PLC. The GitHub reference contains technical details about the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: No
Instructions:
Contact Nanda Automation Technology for firmware updates or patches. No official fix is currently documented.
🔧 Temporary Workarounds
Network Segmentation
allIsolate AT_NA2000 PLCs in separate network segments with strict firewall rules to limit TCP RST packet exposure.
TCP RST Filtering
allConfigure network devices to filter or rate-limit TCP RST packets destined for AT_NA2000 PLCs.
🧯 If You Can't Patch
- Implement strict network access controls to limit which systems can communicate with AT_NA2000 PLCs.
- Deploy network monitoring to detect unusual TCP RST traffic patterns targeting PLCs.
🔍 How to Verify
Check if Vulnerable:
Check if AT_NA2000 PLCs are present in your environment and have TCP/IP networking enabled. No specific vulnerability check command is available.Check Version:
Check PLC firmware version through vendor-specific management interface (no universal command).Verify Fix Applied:
Verify with vendor if firmware updates addressing CVE-2025-56234 are available and applied.📡 Detection & Monitoring
Log Indicators:
- Unusual TCP connection resets in PLC logs
- Network connectivity errors in industrial control system logs
Network Indicators:
- High volume of TCP RST packets to PLC IP addresses
- TCP RST packets with sequence numbers within receive windows
SIEM Query:
source_ip=* AND dest_ip=PLC_IP AND tcp.flags.reset=1 AND count > threshold