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Multiple Okta User Auth Events with Same Device Token Hash Behind a Proxy

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Multiple Okta User Auth Events with Same Device Token Hash Behind a Proxy

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Detects when Okta user authentication events are reported for multiple users with the same device token hash behind a proxy.

Rule type: threshold

Rule indices:

  • filebeat-*
  • logs-okta*

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:

Tags:

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

Version: 206

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Triage and analysis

Investigating Multiple Okta User Auth Events with Same Device Token Hash Behind a Proxy

This rule detects when Okta user authentication events are reported for multiple users with the same device token hash behind a proxy. This may indicate that a shared device between users, or that a user is using a proxy to access multiple accounts for password spraying.

Possible investigation steps:

  • 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.
  • Since the device is behind a proxy, the okta.client.ip field will not be useful for determining the actual device IP address.
  • Review the okta.request.ip_chain field for more information about the geographic location of the proxy.
  • 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.
  • 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.

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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event.dataset:okta.system
    and not okta.actor.id:okta* and okta.debug_context.debug_data.dt_hash:*
    and okta.event_type:user.authentication* and okta.security_context.is_proxy:true

Framework: MITRE ATT&CKTM

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