IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Potential Linux Local Account Brute Force Detected

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Potential Linux Local Account Brute Force Detected

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Identifies multiple consecutive login attempts executed by one process targeting a local linux user account within a short time interval. Adversaries might brute force login attempts across different users with a default wordlist or a set of customly crafted passwords in an attempt to gain access to these accounts.

Rule type: eql

Rule indices:

logs-endpoint.events.*

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: None

Tags:

Domain: Endpoint
OS: Linux
Use Case: Threat Detection
Tactic: Credential Access
Data Source: Elastic Defend

Version: 5

Rule authors:

Elastic

Rule license: Elastic License v2

Setup

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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

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sequence by host.id, process.parent.executable, user.id with maxspan=1s
  [process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and process.name == "su" and
   not process.parent.name in (
     "bash", "dash", "ash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "clickhouse-server", "ma", "gitlab-runner",
     "updatedb.findutils", "cron"
   )
  ] with runs=10

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
Technique:
- Name: Brute Force
- ID: T1110
- Reference URL: https://attack.mitre.org/techniques/T1110/
Sub-technique:
- Name: Password Guessing
- ID: T1110.001
- Reference URL: https://attack.mitre.org/techniques/T1110/001/

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