Attempts to Brute Force an Okta User Account

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Identifies when an Okta user account is locked out 3 times within a 3 hour window. An adversary may attempt a brute force or password spraying attack to obtain unauthorized access to user accounts. The default Okta authentication policy ensures that a user account is locked out after 10 failed authentication attempts.

Rule type: threshold

Rule indices:

  • filebeat-*
  • logs-okta*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-180m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Use Case: Identity and Access Audit
  • Tactic: Credential Access
  • Data Source: Okta

Version: 107

Rule authors:

  • Elastic
  • @BenB196
  • Austin Songer

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Attempts to Brute Force an Okta User Account

Brute force attacks aim to guess user credentials through exhaustive trial-and-error attempts. In this context, Okta accounts are targeted.

This rule fires when an Okta user account has been locked out 3 times within a 3-hour window. This could indicate an attempted brute force or password spraying attack to gain unauthorized access to the user account. Okta's default authentication policy locks a user account after 10 failed authentication attempts.

#### Possible investigation steps:

- Identify the actor related to the alert by reviewing `okta.actor.alternate_id` field in the alert. This should give the username of the account being targeted.
- Review the `okta.event_type` field to understand the nature of the events that led to the account lockout.
- Check the `okta.severity` and `okta.display_message` fields for more context around the lockout events.
- Look for correlation of events from the same IP address. Multiple lockouts from the same IP address might indicate a single source for the attack.
- If the IP is not familiar, investigate it. The IP could be a proxy, VPN, Tor node, cloud datacenter, or a legitimate IP turned malicious.
- Determine if the lockout events occurred during the user's regular activity hours. Unusual timing may indicate malicious activity.
- Examine the authentication methods used during the lockout events by checking the `okta.authentication_context.credential_type` field.

### False positive analysis:

- Determine whether the account owner or an internal user made repeated mistakes in entering their credentials, leading to the account lockout.
- Ensure there are no known network or application issues that might cause these events.

### Response and remediation:

- Alert the user and your IT department immediately.
- If unauthorized access is confirmed, initiate your incident response process.
- Investigate the source of the attack. If a specific machine or network is compromised, additional steps may need to be taken to address the issue.
- Require the affected user to change their password.
- If the attack is ongoing, consider blocking the IP address initiating the brute force attack.
- Implement account lockout policies to limit the impact of brute force attacks.
- Encourage users to use complex, unique passwords and consider implementing multi-factor authentication.
- Check if the compromised account was used to access or alter any sensitive data or systems.

Rule query

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event.dataset:okta.system and event.action:user.account.lock

Framework: MITRE ATT&CKTM