# external\_tcp\_4444 **Explanation** The external\_tcp\_4444 NDM flags connections from outside the customer network to servers on the customer network listening on TCP port 4444. Metasploit uses port 4444 by default for shell listeners that are setup after exploitation, so the use of this port could indicate successful exploitation of a remote code execution vulnerability in a running service on the source host. **What to Look For** Verify that the server (the source IP in this case) is not compromised, and that it is expected to receive connections on port 4444. While traffic to this port could be innocuous, very few networks intentionally expose this service to external hosts. **Related MITRE ATT\&CK Categories** [Initial Access: Exploit Public-Facing Application, Technique T1190 - Enterprise](https://attack.mitre.org/techniques/T1190) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.fusion.vectra.ai/detection-models/library/attack/external_tcp_4444.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.