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« Potential Malware-Driven SSH Brute Force Attempt Successful SSH Authentication from Unusual IP Address »
Elastic Docs ›Elastic Security Solution [8.17] ›Downloadable rule update v8.17.7

Successful SSH Authentication from Unusual SSH Public Key

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Successful SSH Authentication from Unusual SSH Public Key

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This rule leverages the new_terms rule type to detect successful SSH authentications via a public key that has not been seen in the last 10 days. Public key authentication is a secure method for authenticating users to a server. Monitoring unusual public key authentication events can help detect unauthorized access attempts or suspicious activity on the system.

Rule type: new_terms

Rule indices:

  • logs-system.auth-*
  • filebeat-*

Severity: low

Risk score: 21

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: Initial Access
  • Data Source: Elastic Defend

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Setup

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Setup

This rule requires data coming in from one of the following integrations: - Filebeat

Filebeat Setup

Filebeat is a lightweight shipper for forwarding and centralizing log data. Installed as an agent on your servers, Filebeat monitors the log files or locations that you specify, collects log events, and forwards them either to Elasticsearch or Logstash for indexing.

The following steps should be executed in order to add the Filebeat for the Linux System:

  • Elastic provides repositories available for APT and YUM-based distributions. Note that we provide binary packages, but no source packages.
  • To install the APT and YUM repositories follow the setup instructions in this helper guide.
  • To run Filebeat on Docker follow the setup instructions in the helper guide.
  • To run Filebeat on Kubernetes follow the setup instructions in the helper guide.
  • For quick start information for Filebeat refer to the helper guide.
  • For complete Setup and Run Filebeat information refer to the helper guide.

Rule Specific Setup Note

  • This rule requires the Filebeat System Module to be enabled.
  • The system module collects and parses logs created by the system logging service of common Unix/Linux based distributions.
  • To run the system module of Filebeat on Linux follow the setup instructions in the helper guide.

Rule query

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event.category:authentication and host.os.type:linux and event.action:ssh_login and event.outcome:success and system.auth.ssh.method:publickey

Framework: MITRE ATT&CKTM

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