This search, detects execution of suspicious bash commands from various commonly leveraged bash scripts like (AutoSUID, LinEnum, LinPeas) to perform discovery of possible paths of privilege execution, password files, vulnerable directories, executables and file permissions on a Linux host.
The search logic specifically looks for high number of distinct commands run in a short period of time.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-12-06
- Author: Bhavin Patel, Splunk
- ID: 0edd5112-56c9-11ec-b990-acde48001122
Kill Chain Phase
1 2 3 4 5 6 7 8 9 10 | tstats `security_content_summariesonly` count values(Processes.process) values(Processes.process_name) values(Processes.parent_process_name) dc(Processes.process) as distinct_commands dc(Processes.process_name) as distinct_process_names min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where [ |inputlookup linux_tool_discovery_process.csv | rename process as Processes.process |table Processes.process] by _time span=5m Processes.user Processes.dest | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where distinct_commands > 40 AND distinct_process_names > 3 | `suspicious_linux_discovery_commands_filter`
The SPL above uses the following Macros:
suspicious_linux_discovery_commands_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
This detection search is based on Splunk add-on for Microsoft Sysmon-Linux.(https://splunkbase.splunk.com/app/6176/). Please install this add-on to parse fields correctly and execute detection search. Consider customizing the time window and threshold values according to your environment.
Known False Positives
Unless an administrator is using these commands to troubleshoot or audit a system, the execution of these commands should be monitored.
Associated Analytic Story
|81.0||90||90||Suspicious Linux Discovery Commands detected on $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1