Nessus Vulnerability Scanners are falsely being detected by the OfficeScan agent as C&C callback servers even though these vulnerability scanners are authorized to do the said scanning activities. This article will guide you on how to address OfficeScan’s C&C false positive alerts triggered by vulnerability scanner tools like Nessus Vulnerability Scanner.
Vulnerability scanning tools (e.g. Nessus vulnerability scanner) normally send network vulnerability-related traffic to check if a machine is susceptible to a vulnerability. This behavior can trigger one of OfficeScan’s network security protection feature, “Suspicious Connection Service“ which checks for suspicious network packet and flags it as potential C&C callback.
In such scenario, Nessus Vulnerability Scanner can falsely be detected as C&C since it sends vulnerability-related traffic as part of its normal function. The unwanted detection can either trigger unnecessary alerts from trusted source and can also cause disruption of its function if suspicious connection action is set to block.
Here are the recommended steps to address C&C false alarm detection triggered by suspicious connection:
- Confirm if the Callback Address is coming from the Vulnerability Scanner Machine. If internal machines are being flagged as C&C server but do not have similar function as vulnerability scanning tools, further investigation should be conducted for potential malware infection (e.g. collect suspicious files and system information using ATTK, and submit the result to Trend Micro Technical Support for analysis.).
Refer to this article on Generating and Exporting Logs in OfficeScan.
- Once Callback Address machine is verified as vulnerability scanner and is authorized to perform such activity, add the machine’s IP address in the Global User-defined IP List Settings under Approved lists.
You may refer to these articles on configuring global user-defined IP list settings: