Newly Observed IPSEC NAT Traversal Peer
This rule identifies outbound IPSEC NAT Traversal (NAT-T) traffic to an external destination IP that was not observed during the previous 5 days. IPSEC is a VPN technology that allows one system to talk to another…
Description
This rule identifies outbound IPSEC NAT Traversal (NAT-T) traffic to an external destination IP that was not observed during the previous 5 days. IPSEC is a VPN technology that allows one system to talk to another using encrypted tunnels. NAT Traversal encapsulates IPSEC ESP traffic in UDP and, once a NAT device is detected, both peers float to UDP port 4500 for the tunnel data channel. Newly observed external NAT-T peers may indicate unauthorized VPN use or an adversary tunneling command and control or exfiltration traffic over the Internet.
Detection logic
Its licence does not clear it for publishing here
Sunturai publishes a detection's own text where the licence it arrived under has been reviewed and permits it, and Elastic License 2.0 has not. The query as its source wrote it, its canonical form and the hash that pins this revision are in the workspace record.
Detection requirements
- Platform
- ESXiLinuxmacOSNetwork DevicesWindows
The rule states no platform. This is derived from the 3 ATT&CK techniques it maps to.
Known benign triggers
- Newly deployed legitimate site-to-site or client VPN gateways, or established gateways that were inactive for more than 5 days, will generate an alert when first observed. Where these peers are expected, their external destination IP addresses can be excluded.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
No references are available for this detection.
From the source
- At source
- Open at source
- Upstream identifier
- a9cb3641-ff4b-4cdc-a063-b4b8d02a67c7
- Tagged by the source as
- Data Source: Network Packet CaptureData Source: Network TrafficData Source: PAN-OSData Source: pfSenseData Source: ZeekDomain: EndpointDomain: NetworkResources: Investigation GuideRule Type: ES|QLTactic: Command and ControlUse Case: Threat Detection
Licence
- Published under
- Elastic License 2.0Read the licence
- Attribution
- Required
Authorship
- Written by
- Published
- Sep 20, 2026
- Version
- 3