Potential Non-Standard Port SSH connection

Identifies potentially malicious processes communicating via a port paring typically not associated with SSH. For example, SSH over port 2200 or port 2222 as opposed to the traditional port 22. Adversaries may make changes to the standard port a protocol uses to bypass filtering or muddle analysis/parsing of network data.

Rule type: eql

Rule indices:

logs-endpoint.events.*

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://attack.mitre.org/techniques/T1571/

Tags:

Elastic
Host
Linux
Threat Detection
Command and Control
macOS

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

sequence by process.entity_id with maxspan=1m
[process where event.action == "exec" and process.name:"ssh"]
[network where process.name:"ssh"
 and event.action in ("connection_attempted", "connection_accepted")
 and destination.port != 22
 and destination.ip != "127.0.0.1"
 and network.transport: "tcp"
]

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
Technique:
- Name: Non-Standard Port
- ID: T1571
- Reference URL: https://attack.mitre.org/techniques/T1571/

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