Potential Execution of rc.local Script
editPotential Execution of rc.local Script
editThis rule detects the potential execution of the /etc/rc.local script through the already_running event action created by the rc-local.service systemd service. The /etc/rc.local script is a legacy initialization script that is executed at the end of the boot process. The /etc/rc.local script is not enabled by default on most Linux distributions. The /etc/rc.local script can be used by attackers to persistently execute malicious commands or scripts on a compromised system at reboot. As the rc.local file is executed prior to the initialization of Elastic Defend, the execution event is not ingested, and therefore the already_running event is leveraged to provide insight into the potential execution of rc.local.
Rule type: eql
Rule indices:
- logs-endpoint.events.process*
Severity: medium
Risk score: 47
Runs every: 5m
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References:
- https://www.intezer.com/blog/malware-analysis/hiddenwasp-malware-targeting-linux-systems/
- https://pberba.github.io/security/2022/02/06/linux-threat-hunting-for-persistence-initialization-scripts-and-shell-configuration/#8-boot-or-logon-initialization-scripts-rc-scripts
- https://www.cyberciti.biz/faq/how-to-enable-rc-local-shell-script-on-systemd-while-booting-linux-system/
Tags:
- Domain: Endpoint
- OS: Linux
- Use Case: Threat Detection
- Tactic: Persistence
- Data Source: Elastic Defend
Version: 1
Rule authors:
- Elastic
Rule license: Elastic License v2
Setup
editSetup
This rule requires data coming in from Elastic Defend.
Elastic Defend Integration Setup
Elastic Defend is integrated into the Elastic Agent using Fleet. Upon configuration, the integration allows the Elastic Agent to monitor events on your host and send data to the Elastic Security app.
Prerequisite Requirements:
- Fleet is required for Elastic Defend.
- To configure Fleet Server refer to the documentation.
The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
- Go to the Kibana home page and click "Add integrations".
- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
- Click "Add Elastic Defend".
- Configure the integration name and optionally add a description.
- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
- Select a configuration preset. Each preset comes with different default settings for Elastic Agent, you can further customize these later by configuring the Elastic Defend integration policy. Helper guide.
- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
- Enter a name for the agent policy in "New agent policy name". If other agent policies already exist, you can click the "Existing hosts" tab and select an existing policy instead. For more details on Elastic Agent configuration settings, refer to the helper guide.
- Click "Save and Continue".
- To complete the integration, select "Add Elastic Agent to your hosts" and continue to the next section to install the Elastic Agent on your hosts. For more details on Elastic Defend refer to the helper guide.
Rule query
editprocess where host.os.type == "linux" and event.type == "info" and event.action == "already_running" and process.parent.args == "/etc/rc.local" and process.parent.args == "start"
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
-
Technique:
- Name: Boot or Logon Initialization Scripts
- ID: T1037
- Reference URL: https://attack.mitre.org/techniques/T1037/
-
Sub-technique:
- Name: RC Scripts
- ID: T1037.004
- Reference URL: https://attack.mitre.org/techniques/T1037/004/