Detection: Linux SSH Remote Services Script Execute

Description

The following analytic detects the use of SSH to move laterally and execute a script or file on a remote host. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on specific SSH command-line parameters and URLs. This activity is significant as it may indicate an attacker attempting to execute remote commands or scripts, potentially leading to unauthorized access or control over additional systems. If confirmed malicious, this could result in lateral movement, privilege escalation, or the execution of malicious payloads, compromising the security of the network.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where  Processes.process_name=ssh Processes.process IN ("*oStrictHostKeyChecking*", "*oConnectTimeout*", "*oBatchMode*") AND Processes.process IN ("*http:*","*https:*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `linux_ssh_remote_services_script_execute_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon for Linux EventID 1	Linux	'sysmon:linux'	'Syslog:Linux-Sysmon/Operational'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

This is not a common command to be executed. Filter as needed.

Associated Analytic Story

• Linux Living Off The Land

Risk Based Analytics (RBA)

References

• https://redcanary.com/blog/lateral-movement-with-secure-shell/

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4