|The following analytic identifies curl with the command-line switches that are commonly used to download, output, a remote script or binary. MetaSploit Framework will combine the -sO switch with||chmod +x to enable a simple one liner to download and set the execute bit to run the file immediately. During triage, review the remote domain and file being downloaded for legitimacy.|
- Type: Anomaly
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2022-07-29
- Author: Michael Haag, Splunk
- ID: 8c1de57d-abc1-4b41-a727-a7a8fc5e0857
Kill Chain Phase
- Command and Control
- CIS 10
1 2 3 4 5 6 7 8 9 10 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=curl by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where match(process, "(?i)(-O |-sO |-ksO |--output)") | `linux_ingress_tool_transfer_with_curl_filter`
The SPL above uses the following Macros:
linux_ingress_tool_transfer_with_curl_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
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
False positives will be present. Tune and then change type to TTP.
Associated Analytic Story
|12.0||40||30||An instance of $process_name$ was identified on endpoint $dest$ by user $user$ to download a remote file. Review activity for further details.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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