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Multiple Device Token Hashes for Single Okta Session

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Multiple Device Token Hashes for Single Okta Session

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This rule detects when a specific Okta actor has multiple device token hashes for a single Okta session. This may indicate an authenticated session has been hijacked or is being used by multiple devices. Adversaries may hijack a session to gain unauthorized access to Okta admin console, applications, tenants, or other resources.

Rule type: esql

Rule indices: None

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
  • Domain: SaaS

Version: 304

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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Triage and analysis

Investigating Multiple Device Token Hashes for Single Okta Session

This rule detects when a specific Okta actor has multiple device token hashes for a single Okta session. This may indicate an authenticated session has been hijacked or is being used by multiple devices. Adversaries may hijack a session to gain unauthorized access to Okta admin console, applications, tenants, or other resources.

Possible investigation steps:

  • Since this is an ES|QL rule, the okta.actor.alternate_id and okta.authentication_context.external_session_id values can be used to pivot into the raw authentication events related to this alert.
  • 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.
  • 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.
  • Authentication events have been filtered out to focus on Okta activity via established sessions.
  • 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.
  • Aggregate by okta.actor.alternate_id and event.action to determine the type of actions that are being performed by the actor(s) involved in this action.
  • If various activity is reported that seems to indicate actions from separate users, consider deactivating the user’s account temporarily.

False positive analysis:

  • It is very rare that a legitimate user would have multiple device token hashes for a single Okta session as DT hashes do not change after an authenticated session is established.

Response and remediation:

  • Consider stopping all sessions for the user(s) involved in this action.
  • If this does not appear to be a false positive, consider resetting passwords for the users involved 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.
  • 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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Setup

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"
    // ignore authentication events where session and device token hash change often
    AND NOT event.action IN (
        "policy.evaluate_sign_on",
        "user.session.start",
        "user.authentication.sso"
    )
    // ignore Okta system events and only allow registered users
    AND (
        okta.actor.alternate_id != "system@okta.com"
        AND okta.actor.alternate_id RLIKE "[^@\\s]+\\@[^@\\s]+"
    )
    AND okta.authentication_context.external_session_id != "unknown"
| KEEP event.action, okta.actor.alternate_id, okta.authentication_context.external_session_id, okta.debug_context.debug_data.dt_hash
| STATS
    dt_hash_counts = COUNT_DISTINCT(okta.debug_context.debug_data.dt_hash) BY
        okta.actor.alternate_id,
        okta.authentication_context.external_session_id
| WHERE
    dt_hash_counts >= 2
| SORT
    dt_hash_counts DESC

Framework: MITRE ATT&CKTM

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