Name:Linux Adding Crontab Using List Parameter id:52f6d751-1fd4-4c74-a4c9-777ecfeb5c58 version:6 date:2025-02-10 author:Teoderick Contreras, Splunk status:production type:Hunting Description:The following analytic detects suspicious modifications to cron jobs on Linux systems using the crontab command with list parameters. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. This activity is significant as it may indicate an attempt to establish persistence or execute malicious code on a schedule. If confirmed malicious, the impact could include unauthorized code execution, data destruction, or other damaging outcomes. Further investigation should analyze the added cron job, its associated command, and any related processes. Data_source:
-Sysmon for Linux EventID 1
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "crontab" Processes.process= "* -l*" by Processes.action Processes.dest Processes.original_file_name Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `linux_adding_crontab_using_list_parameter_filter`
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:Administrator or network operator can use this application for automation purposes. Please update the filter macros to remove false positives. References: -https://www.welivesecurity.com/2022/04/12/industroyer2-industroyer-reloaded/ -https://cert.gov.ua/article/39518 drilldown_searches:
: tags: analytic_story: - 'Industroyer2' - 'Linux Privilege Escalation' - 'Linux Living Off The Land' - 'Data Destruction' - 'Linux Persistence Techniques' - 'Scheduled Tasks' - 'Gomir' asset_type:Endpoint mitre_attack_id: - 'T1053.003' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:endpoint
