IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Azure External Guest User Invitation

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Azure External Guest User Invitation

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Identifies an invitation to an external user in Azure Active Directory (AD). Azure AD is extended to include collaboration, allowing you to invite people from outside your organization to be guest users in your cloud account. Unless there is a business need to provision guest access, it is best practice avoid creating guest users. Guest users could potentially be overlooked indefinitely leading to a potential vulnerability.

Rule type: query

Rule indices:

filebeat-*
logs-azure*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-25m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://docs.microsoft.com/en-us/azure/governance/policy/samples/cis-azure-1-1-0

Tags:

Elastic
Cloud
Azure
Continuous Monitoring
SecOps
Identity and Access

Version: 7 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Guest user invitations may be sent out by a system or network administrator. Verify whether the username, hostname, and/or resource name should be making changes in your environment. Guest user invitations from unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.

Investigation guide

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Rule query

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event.dataset:azure.auditlogs and
azure.auditlogs.operation_name:"Invite external user" and
azure.auditlogs.properties.target_resources.*.display_name:guest and
event.outcome:(Success or success)

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Valid Accounts
- ID: T1078
- Reference URL: https://attack.mitre.org/techniques/T1078/
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Valid Accounts
- ID: T1078
- Reference URL: https://attack.mitre.org/techniques/T1078/

Rule version history

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Version 7 (8.4.0 release)

Formatting only

Version 5 (7.13.0 release)

Formatting only

Version 4 (7.12.0 release)

Formatting only

Version 3 (7.11.2 release)

Formatting only

Version 2 (7.11.0 release)

Updated query, changed from:

event.dataset:azure.auditlogs and
azure.auditlogs.operation_name:"Invite external user" and
azure.auditlogs.properties.target_resources.*.display_name:guest and
event.outcome:Success

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