> For the complete documentation index, see [llms.txt](https://docs.fusion.vectra.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fusion.vectra.ai/detection-models/library/operational-governance/messaging_signal.md). # messaging\_signal **Explanation** The messaging\_signal NDM is designed to detect the presence of the Signal messaging application on the network. Signal is an end to end encrypted messaging application that can be used for legitimate or malicious purposes. **What to Look For** To examine the results of this NDM Event, check for any outgoing or incoming Signal traffic on the network. This can be done by analyzing network traffic logs or using network monitoring tools. Additionally, it is recommended to check all endpoints for the presence of Signal installed or running in the background. If Signal is detected on a corporate endpoint, it is important to investigate further to ensure its usage is legitimate. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## 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/operational-governance/messaging_signal.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.