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Multiple Okta User Authentication Events with Client Address

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Multiple Okta User Authentication Events with Client Address

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Detects when a certain threshold of Okta user authentication events are reported for multiple users from the same client address. Adversaries may attempt to launch a credential stuffing or password spraying attack from the same device by using a list of known usernames and passwords to gain unauthorized access to user accounts.

Rule type: esql

Rule indices: None

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:

Tags:

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

Version: 3

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Triage and analysis

Investigating Multiple Okta User Authentication Events with Client Address

This rule detects when a certain threshold of Okta user authentication events are reported for multiple users from the same client address. Adversaries may attempt to launch a credential stuffing attack from the same device by using a list of known usernames and passwords to gain unauthorized access to user accounts. Note that Okta does not log unrecognized usernames supplied during authentication attempts, so this rule may not detect all credential stuffing attempts or may indicate a targeted attack.

Possible investigation steps:

Since this is an ES|QL rule, the okta.actor.alternate_id and okta.client.ip values can be used to pivot into the raw authentication events related to this activity. - Identify the users involved in this action by examining the okta.actor.id, okta.actor.type, okta.actor.alternate_id, and okta.actor.display_name fields. - Determine the device client used for these actions by analyzing okta.client.ip, okta.client.user_agent.raw_user_agent, okta.client.zone, okta.client.device, and okta.client.id fields. - Review the okta.security_context.is_proxy field to determine if the device is a proxy. - If the device is a proxy, this may indicate that a user is using a proxy to access multiple accounts for password spraying. - With the list of okta.actor.alternate_id values, review event.outcome results to determine if the authentication was successful. - If the authentication was successful for any user, pivoting to event.action values for those users may provide additional context. - With Okta end users identified, review the okta.debug_context.debug_data.dt_hash field. - Historical analysis should indicate if this device token hash is commonly associated with the user. - Review the okta.event_type field to determine the type of authentication event that occurred. - If the event type is user.authentication.sso, the user may have legitimately started a session via a proxy for security or privacy reasons. - If the event type is user.authentication.password, the user may be using a proxy to access multiple accounts for password spraying. - If the event type is user.session.start, the source may have attempted to establish a session via the Okta authentication API. - Examine the okta.outcome.result field to determine if the authentication was successful. - Review the past activities of the actor(s) involved in this action by checking their previous actions. - Evaluate the actions that happened just before and after this event in the okta.event_type field to help understand the full context of the activity. - This may help determine the authentication and authorization actions that occurred between the user, Okta and application.

False positive analysis:

  • A user may have legitimately started a session via a proxy for security or privacy reasons.
  • Users may share an endpoint related to work or personal use in which separate Okta accounts are used.
  • Architecturally, this shared endpoint may leverage a proxy for security or privacy reasons.
  • Shared systems such as Kiosks and conference room computers may be used by multiple users.
  • Shared working spaces may have a single endpoint that is used by multiple users.

Response and remediation:

  • Review the profile of the users involved in this action to determine if proxy usage may be expected.
  • If the user is legitimate and the authentication behavior is not suspicious based on device analysis, no action is required.
  • If the user is legitimate but the authentication behavior is suspicious, consider resetting passwords for the users involves and enabling multi-factor authentication (MFA).
  • If MFA is already enabled, consider resetting MFA for the users.
  • If any of the users are not legitimate, consider deactivating the user’s account.
  • Conduct a review of Okta policies and ensure they are in accordance with security best practices.
  • Check with internal IT teams to determine if the accounts involved recently had MFA reset at the request of the user.
  • If so, confirm with the user this was a legitimate request.
  • If so and this was not a legitimate request, consider deactivating the user’s account temporarily.
  • Reset passwords and reset MFA for the user.
  • If this is a false positive, consider adding the okta.debug_context.debug_data.dt_hash field to the exceptions list in the rule.
  • This will prevent future occurrences of this event for this device from triggering the rule.
  • Alternatively adding okta.client.ip or a CIDR range to the exceptions list can prevent future occurrences of this event from triggering the rule.
  • This should be done with caution as it may prevent legitimate alerts from being generated.

Setup

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The Okta Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.

Rule query

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FROM logs-okta*
| WHERE
    event.dataset == "okta.system"
    AND (event.action == "user.session.start" OR event.action RLIKE "user\\.authentication(.*)")
    AND okta.outcome.reason == "INVALID_CREDENTIALS"
| KEEP okta.client.ip, okta.actor.alternate_id, okta.actor.id, event.action, okta.outcome.reason
| STATS
    source_auth_count = COUNT_DISTINCT(okta.actor.id)
    BY okta.client.ip, okta.actor.alternate_id
| WHERE
    source_auth_count > 5
| SORT
    source_auth_count DESC

Framework: MITRE ATT&CKTM

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