Entra ID OAuth PRT Issuance to Non-Managed Device Detected

  1[metadata]
  2creation_date = "2025/06/24"
  3integration = ["azure"]
  4maturity = "production"
  5updated_date = "2026/09/18"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Identifies when a user signs in with a refresh token using the Microsoft Authentication Broker (MAB) client, followed by
 11a Primary Refresh Token (PRT) sign-in from the same device within 1 hour from an unmanaged device. This pattern may indicate that an attacker has
 12successfully registered a device using ROADtx and transitioned from short-term token access to long-term persistent
 13access via PRTs. Excluding access to the Device Registration Service (DRS) ensures the PRT is being used beyond
 14registration, often to access Microsoft 365 resources like Outlook or SharePoint.
 15"""
 16from = "now-60m"
 17index = ["filebeat-*", "logs-azure.signinlogs-*"]
 18interval = "30m"
 19language = "eql"
 20license = "Elastic License v2"
 21name = "Entra ID OAuth PRT Issuance to Non-Managed Device Detected"
 22note = """## Triage and analysis
 23
 24### Investigating Entra ID OAuth PRT Issuance to Non-Managed Device Detected
 25
 26This rule identifies a sequence where a Microsoft Entra ID authenticates using a refresh token issued to the Microsoft Authentication Broker (MAB), followed by an authentication using a Primary Refresh Token (PRT) from the same unmanaged device. This behavior is uncommon for normal user activity and strongly suggests adversarial behavior, particularly when paired with OAuth phishing and device registration tools like ROADtx. The use of PRT shortly after a refresh token sign-in typically indicates the attacker has registered a virtual device and is now using the PRT to impersonate a registered user+device pair. The device in question is still marked as unmanaged, indicating it is not compliant with organizational policies and managed by Intune or other MDM solutions.
 27
 28### Possible investigation steps
 29- Identify the user principal and device from `azure.signinlogs.properties.user_principal_name` and `azure.signinlogs.properties.device_detail.device_id`.
 30- Confirm the first sign-in event came from the Microsoft Auth Broker (`app_id`) with `incoming_token_type: refreshToken`.
 31- Ensure the device has a `trust_type` of "Azure AD joined" and that the `sign_in_session_status` is "unbound".
 32- Confirm the second sign-in used `incoming_token_type: primaryRefreshToken` and that the `resource_display_name` is not "Device Registration Service".
 33- Investigate any Microsoft Graph, Outlook, or SharePoint access occurring shortly after.
 34- Review conditional access policy outcomes and determine whether MFA or device compliance was bypassed.
 35
 36### False positive analysis
 37- Legitimate device onboarding and sign-ins using hybrid-joined endpoints may trigger this rule.
 38- Rapid device provisioning in enterprise environments using MAB could generate similar token behavior.
 39- Use supporting signals, such as IP address changes, geolocation, or user agent anomalies, to reduce noise.
 40
 41### Response and remediation
 42- Investigate other sign-in patterns and assess whether token abuse has occurred.
 43- Revoke PRT sessions via Microsoft Entra ID or Conditional Access.
 44- Remove or quarantine the suspicious device registration.
 45- Require password reset and enforce MFA.
 46- Audit and tighten device trust and conditional access configurations.
 47"""
 48references = [
 49    "https://www.volexity.com/blog/2025/04/22/phishing-for-codes-russian-threat-actors-target-microsoft-365-oauth-workflows/",
 50    "https://dirkjanm.io/abusing-azure-ad-sso-with-the-primary-refresh-token/",
 51]
 52risk_score = 47
 53rule_id = "40e60816-5122-11f0-9caa-f661ea17fbcd"
 54severity = "medium"
 55tags = [
 56    "Domain: Cloud",
 57    "Domain: Identity",
 58    "Use Case: Threat Detection",
 59    "Data Source: Azure",
 60    "Data Source: Microsoft Entra ID",
 61    "Data Source: Microsoft Entra ID Sign-In Logs",
 62    "Tactic: Persistence",
 63    "Tactic: Initial Access",
 64    "Resources: Investigation Guide",
 65    "Noise: Medium",
 66    "Performance: Fast",
 67    "Profile: Recommended",
 68    "Threat: Device Code Phishing",
 69    "Rule Type: Event Correlation (EQL)",
 70    "Platform: Entra ID",
 71]
 72timestamp_override = "event.ingested"
 73type = "eql"
 74
 75query = '''
 76sequence by azure.signinlogs.properties.user_id, azure.signinlogs.properties.device_detail.device_id with maxspan=1h
 77  [authentication where
 78    data_stream.dataset == "azure.signinlogs" and
 79    azure.signinlogs.category == "NonInteractiveUserSignInLogs" and
 80    azure.signinlogs.properties.app_id == "29d9ed98-a469-4536-ade2-f981bc1d605e" and
 81    azure.signinlogs.properties.incoming_token_type == "refreshToken" and
 82    azure.signinlogs.properties.device_detail.trust_type == "Azure AD joined" and
 83    azure.signinlogs.properties.device_detail.device_id != null and
 84    azure.signinlogs.properties.token_protection_status_details.sign_in_session_status == "unbound" and
 85    azure.signinlogs.properties.user_type == "Member" and
 86    azure.signinlogs.result_signature == "SUCCESS"
 87  ]
 88  [authentication where
 89    data_stream.dataset == "azure.signinlogs" and
 90    azure.signinlogs.properties.incoming_token_type == "primaryRefreshToken" and
 91    azure.signinlogs.properties.resource_display_name != "Device Registration Service" and
 92    azure.signinlogs.result_signature == "SUCCESS" and
 93    azure.signinlogs.properties.device_detail.is_managed != true
 94    and not (
 95        azure.signinlogs.properties.app_display_name == "Windows Sign In" or
 96        user_agent.original == "Windows-AzureAD-Authentication-Provider/1.0"
 97    )
 98  ]
 99'''
100
101[rule.investigation_fields]
102field_names = [
103    "azure.signinlogs.properties.user_principal_name",
104    "azure.signinlogs.properties.device_detail.device_id",
105    "azure.signinlogs.properties.incoming_token_type",
106    "azure.signinlogs.properties.resource_display_name",
107    "azure.signinlogs.properties.token_protection_status_details.sign_in_session_status",
108    "azure.signinlogs.properties.app_id",
109    "azure.signinlogs.properties.device_detail.trust_type",
110    "source.geo.country_name",
111    "source.geo.city_name",
112    "source.address",
113    "event.outcome",
114    "event.category",
115]
116
117[[rule.threat]]
118framework = "MITRE ATT&CK"
119
120[[rule.threat.technique]]
121id = "T1078"
122name = "Valid Accounts"
123reference = "https://attack.mitre.org/techniques/T1078/"
124
125[[rule.threat.technique.subtechnique]]
126id = "T1078.004"
127name = "Cloud Accounts"
128reference = "https://attack.mitre.org/techniques/T1078/004/"
129
130[[rule.threat.technique]]
131id = "T1098"
132name = "Account Manipulation"
133reference = "https://attack.mitre.org/techniques/T1098/"
134
135[[rule.threat.technique.subtechnique]]
136id = "T1098.005"
137name = "Device Registration"
138reference = "https://attack.mitre.org/techniques/T1098/005/"
139
140[rule.threat.tactic]
141id = "TA0003"
142name = "Persistence"
143reference = "https://attack.mitre.org/tactics/TA0003/"
144
145[[rule.threat]]
146framework = "MITRE ATT&CK"
147
148[[rule.threat.technique]]
149id = "T1528"
150name = "Steal Application Access Token"
151reference = "https://attack.mitre.org/techniques/T1528/"
152
153[rule.threat.tactic]
154id = "TA0006"
155name = "Credential Access"
156reference = "https://attack.mitre.org/tactics/TA0006/"
157
158[[rule.threat]]
159framework = "MITRE ATT&CK"
160
161[rule.threat.tactic]
162id = "TA0001"
163name = "Initial Access"
164reference = "https://attack.mitre.org/tactics/TA0001/"
165
166[[rule.threat]]
167framework = "MITRE ATT&CK"
168
169[[rule.threat.technique]]
170id = "T1550"
171name = "Use Alternate Authentication Material"
172reference = "https://attack.mitre.org/techniques/T1550/"
173
174[[rule.threat.technique.subtechnique]]
175id = "T1550.001"
176name = "Application Access Token"
177reference = "https://attack.mitre.org/techniques/T1550/001/"
178
179[rule.threat.tactic]
180id = "TA0005"
181name = "Defense Evasion"
182reference = "https://attack.mitre.org/tactics/TA0005/"