((full)) — Nhdta-793

| Action | Description | Priority | |--------|-------------|----------| | | Upgrade to NHDTA v3.5.0 (or later) – the patch replaces the unsafe deserialization with a whitelist of allowed classes and validates the JSON schema. | Critical | | Network segmentation | Restrict inbound access to the HTTP API ( port 8080 ) to trusted IP ranges only. Use firewall rules or a reverse‑proxy with authentication. | High | | Enable Java Security Manager (if feasible) | Deploy the agent with -Djava.security.manager and a custom policy that denies java.io.Serializable deserialization of untrusted data. | Medium | | Remove vulnerable libraries | Replace commons-collections:3.1 with a patched version ( commons-collections4 ) or use the commons-collections 3.2.2 release that disables the vulnerable InvokerTransformer . | High | | Input validation | Add a JSON schema validator in front of the API that rejects any payload field that is not a proper Base64‑encoded string of a known format. | Medium | | Monitoring & detection | Deploy IDS/IPS signatures (Snort/Suricata) for the known ysoserial payload pattern, and enable logging of all POST requests to /api/v1/transfer . | High | | File integrity monitoring | Watch for creation of suspicious files (e.g., /tmp/pwned , new cron jobs) using tools such as Tripwire , OSSEC , or Microsoft Defender ATP . | High | | Incident response | If exploitation is suspected, isolate the host, collect forensic artefacts (memory dump, /var/log/nhdta/*.log ), and rotate all credentials that may have been exposed. | Critical |

After upgrading, confirm the fix is present: nhdta-793

# Verify class version jar tf nhdta-3.5.0.jar | grep TransferHandler.class # Decompile (or use `javap -c`) to ensure ObjectInputStream is no longer used directly. | High | | Enable Java Security Manager

After the request returns 200 OK , check the target for the indicator file: | Medium | | Monitoring & detection |