By default the Tenable Add-on for Splunk will pull ALL data the user we are configured to connect with has access to in Tenable.sc. There are obviously options on the Input for Tenable.sc that could limit this data a bit, but if you arent using/setting these it will pull everything. When you are comparing what you see in T.sc to what is in Splunk we recommend the following:
In T.sc login as the user configured for Splunk to use to pull data and go to the analysis ->vulnerabilities page and select the Vulnerability Detail List View. In the upper right-hand corner should be the total number of vulnerabilities you should see in Splunk.
In Splunk search against the index you have configured for your input for sourcetype="tenable:sc:vulns" | dedup ip, pluginID, port, protocol |search state!=fixed with a search window of All Time.
The way the current app stores data limits how much data we store drastically, but requires searches to be for all time as vulnerabilities are only indexed once based on their firstSeen time and never updated until their state changes.
Our V2 app that went EA yesterday changes all of this drastically so you may want to chat with your Tenable PoC about what is in the next version and all the changes it will provide.
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