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Potential Successful Linux FTP Brute Force Attack Detected

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Potential Successful Linux FTP Brute Force Attack Detected

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An FTP (file transfer protocol) brute force attack is a method where an attacker systematically tries different combinations of usernames and passwords to gain unauthorized access to an FTP server, and if successful, the impact can include unauthorized data access, manipulation, or theft, compromising the security and integrity of the server and potentially exposing sensitive information. This rule identifies multiple consecutive authentication failures targeting a specific user account from the same source address and within a short time interval, followed by a successful authentication.

Rule type: eql

Rule indices:

auditbeat-*
logs-auditd_manager.auditd-*

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

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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## Setup
This rule requires the use of the `auditd_manager` integration. `Auditd_manager` is a tool designed to simplify and enhance the management of the audit subsystem in Linux systems. It provides a user-friendly interface and automation capabilities for configuring and monitoring system auditing through the auditd daemon. With `auditd_manager`, administrators can easily define audit rules, track system events, and generate comprehensive audit reports, improving overall security and compliance in the system. The following steps should be executed in order to install and deploy `auditd_manager` on a Linux system.
```
Kibana -->
Management -->
Integrations -->
Auditd Manager -->
Add Auditd Manager
```
`Auditd_manager` subscribes to the kernel and receives events as they occur without any additional configuration. However, if more advanced configuration is required to detect specific behavior, audit rules can be added to the integration in either the "audit rules" configuration box or the "auditd rule files" box by specifying a file to read the audit rules from.
```
For this detection rule no additional audit rules are required to be added to the integration.
```
Add the newly installed `auditd manager` to an agent policy, and deploy the agent on a Linux system from which auditd log files are desirable.

Rule query

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sequence by host.id, auditd.data.addr, related.user with maxspan=5s
  [authentication where host.os.type == "linux" and event.dataset == "auditd_manager.auditd" and
   event.action == "authenticated" and auditd.data.terminal == "ftp" and event.outcome == "failure" and
   auditd.data.addr != null and auditd.data.addr != "0.0.0.0" and auditd.data.addr != "::"] with runs=10
  [authentication where host.os.type == "linux" and event.dataset == "auditd_manager.auditd" and
   event.action  == "authenticated" and auditd.data.terminal == "ftp" and event.outcome == "success" and
   auditd.data.addr != null and auditd.data.addr != "0.0.0.0" and auditd.data.addr != "::"] | tail 1

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/
Sub-technique:
- Name: Password Spraying
- ID: T1110.003
- Reference URL: https://attack.mitre.org/techniques/T1110/003/

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