Cisco Secure Firewall - Potential Large Outbound Data Transfer

This analytic detects potentially suspicious large outbound data transfers from internal to external networks using Cisco Secure Firewall Threat Defense logs. It calculates the total volume of data exchanged per connection by summing InitiatorBytes and ResponderBytes. Connections exceeding 100 MB are flagged, as these may indicate unauthorized data exfiltration, especially if initiated by unusual users, hosts, or processes. The detection is scoped to inside-to-outside network flows. If confirmed malicious, this behavior may reflect data staging and exfiltration over an encrypted or stealthy transport.