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
Risk score: 21
Runs every: 5 minutes
Maximum alerts per execution: 100
- Threat Detection
- Command and Control
Added (Elastic Stack release): 8.6.0
Rule authors: Elastic
Rule license: Elastic License v2
SSH over ports apart from the traditional port 22 is highly uncommon. This rule alerts the usage of the such uncommon ports by the ssh service. Tuning is needed to have higher confidence. If this activity is expected and noisy in your environment, consider adding exceptions — preferably with a combination whitelisted ports for such legitimate ssh activities.
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" ]