EXPLORE DETECTIONS
M365 Exchange Inbox Phishing Evasion Rule Created
Identifies when a user creates a new inbox rule in Microsoft 365 that deletes or moves emails containing suspicious keywords. Adversaries who have compromised accounts often create inbox rules to hide alerts, security notifications, or other sensitive messages by automatically deleting them or moving them to obscure folders. Common destinations include Deleted Items, Junk Email, RSS Feeds, and RSS Subscriptions. This is a New Terms rule that triggers only when the user principal name and associated source IP address have not been observed performing this activity in the past 14 days.
M365 Exchange Mail Flow Transport Rule Created
Identifies a transport rule creation in Microsoft 365. As a best practice, Exchange Online mail transport rules should not be set to forward email to domains outside of your organization. An adversary may create transport rules to exfiltrate data.
M365 Exchange Mail Flow Transport Rule Modified
Identifies when a transport rule has been disabled or deleted in Microsoft 365. Mail flow rules (also known as transport rules) are used to identify and take action on messages that flow through your organization. An adversary or insider threat may modify a transport rule to exfiltrate data or evade defenses.
M365 Exchange Mailbox Accessed by Unusual Client
Identifies suspicious Microsoft 365 mail access by ClientAppId. This rule detects when a user accesses their mailbox using a client application that is not typically used by the user, which may indicate potential compromise or unauthorized access attempts. Adversaries may use custom or third-party applications to access mailboxes, bypassing standard security controls. First-party Microsoft applications are also abused after OAuth tokens are compromised, allowing adversaries to access mailboxes without raising suspicion.
M365 Exchange Mailbox Audit Logging Bypass Added
Detects the occurrence of mailbox audit bypass associations. The mailbox audit is responsible for logging specified mailbox events (like accessing a folder or a message or permanently deleting a message). However, actions taken by some authorized accounts, such as accounts used by third-party tools or accounts used for lawful monitoring, can create a large number of mailbox audit log entries and may not be of interest to your organization. Because of this, administrators can create bypass associations, allowing certain accounts to perform their tasks without being logged. Attackers can abuse this allowlist mechanism to conceal actions taken, as the mailbox audit will log no activity done by the account.
M365 Exchange Mailbox High-Risk Permission Delegated
Identifies the assignment of rights to access content from another mailbox. An adversary may use the compromised account to send messages to other accounts in the network of the target organization while creating inbox rules, so messages can evade spam/phishing detection mechanisms.
M365 Exchange Mailbox Items Accessed Excessively
Identifies an excessive number of Microsoft 365 mailbox items accessed by a user either via aggregated counts or throttling. Microsoft audits mailbox access via the MailItemsAccessed event, which is triggered when a user accesses mailbox items. If more than 1000 mailbox items are accessed within a 24-hour period, it is then throttled. Excessive mailbox access may indicate an adversary attempting to exfiltrate sensitive information or perform reconnaissance on a target's mailbox. This rule detects both the throttled and unthrottled events with a high threshold.
M365 Exchange Malware Filter Policy Deleted
Identifies when a malware filter policy has been deleted in Microsoft 365. A malware filter policy is used to alert administrators that an internal user sent a message that contained malware. This may indicate an account or machine compromise that would need to be investigated. Deletion of a malware filter policy may be done to evade detection.
M365 Exchange Malware Filter Rule Modified
Identifies when a malware filter rule has been deleted or disabled in Microsoft 365. An adversary or insider threat may want to modify a malware filter rule to evade detection.
M365 Exchange Management Group Role Assigned
Identifies when a new role is assigned to a management group in Microsoft 365. An adversary may attempt to add a role in order to maintain persistence in an environment.
M365 Exchange MFA Notification Email Deleted or Moved
Identifies when an MFA enrollment, registration, or security notification email is deleted or moved to deleted items in Microsoft 365 Exchange. Adversaries who compromise accounts and register their own MFA device often delete the notification emails to cover their tracks and prevent the legitimate user from noticing the unauthorized change. This technique is commonly observed in business email compromise (BEC) and account takeover attacks.
M365 Identity Global Administrator Role Assigned
Identifies when the Microsoft 365 Global Administrator or Company Administrator role is assigned to a user or service principal. The Global Administrator role has extensive privileges across Entra ID and Microsoft 365 services, making it a high-value target for adversaries seeking persistent access. Successful assignments of this role may indicate potential privilege escalation or unauthorized access attempts, especially if performed by accounts that do not typically manage high-privilege roles.
M365 Identity Login from Atypical Travel Location
Detects successful Microsoft 365 portal logins from rare locations. Rare locations are defined as locations that are not commonly associated with the user's account. This behavior may indicate an adversary attempting to access a Microsoft 365 account from an unusual location or behind a VPN.
M365 Identity Login from Impossible Travel Location
Detects successful Microsoft 365 portal logins from impossible travel locations. Impossible travel locations are defined as two different countries within a short time frame. This behavior may indicate an adversary attempting to access a Microsoft 365 account from a compromised account or a malicious actor attempting to access a Microsoft 365 account from a different location.
M365 Identity OAuth Flow by First-Party Microsoft App from Multiple IPs
Identifies sign-ins on behalf of a principal user to the Microsoft Graph or legacy Azure AD API from multiple IPs using first-party Microsoft applications from the FOCI (Family of Client IDs) group. Developer tools like Azure CLI, VSCode, and Azure PowerShell accessing these resources from multiple IPs are flagged, along with any FOCI application accessing the deprecated Windows Azure Active Directory from multiple IPs. This behavior may indicate an adversary using a phished OAuth authorization code or refresh token, as seen in attacks like ConsentFix where attackers steal localhost OAuth codes and replay them from attacker infrastructure.
M365 Identity OAuth Flow by User Sign-in to Device Registration
Identifies attempts to register a new device in Microsoft Entra ID after OAuth authentication with authorization code grant. Adversaries may use OAuth phishing techniques to obtain an OAuth authorization code, which can then be exchanged for access and refresh tokens. This rule detects a sequence of events where a user principal authenticates via OAuth, followed by a device registration event, indicating potential misuse of the OAuth flow to establish persistence or access resources.
M365 Identity OAuth Illicit Consent Grant by Rare Client and User
Identifies an Microsoft 365 illicit consent grant request on-behalf-of a registered Entra ID application. Adversaries may create and register an application in Microsoft Entra ID for the purpose of requesting user consent to access resources in Microsoft 365. This is accomplished by tricking a user into granting consent to the application, typically via a pre-made phishing URL. This establishes an OAuth grant that allows the malicious client applocation to access resources in Microsoft 365 on-behalf-of the user.
M365 Identity OAuth Phishing via First-Party Microsoft Application
Detects potentially suspicious OAuth authorization activity in Microsoft 365 where first-party Microsoft applications from the FOCI (Family of Client IDs) group request access to Microsoft Graph or legacy Azure AD resources. Developer tools like Azure CLI, Visual Studio Code, and Azure PowerShell accessing these resources are flagged, as they are commonly abused in phishing campaigns like ConsentFix. Additionally, any FOCI family application accessing the deprecated Windows Azure Active Directory resource is flagged since this API is rarely used legitimately and attackers target it for stealth. First-party apps are trusted by default in all tenants and cannot be blocked, making them ideal for OAuth phishing attacks.
M365 Identity Unusual SSO Authentication Errors for User
Identifies the first occurrence of SSO, SAML, or federated authentication errors for a user. These errors may indicate token manipulation, SAML assertion tampering, or OAuth phishing attempts. Modern adversaries often target SSO mechanisms through token theft, SAML response manipulation, or exploiting federated authentication weaknesses rather than traditional brute force attacks.
M365 Identity User Account Lockouts
Detects a burst of Microsoft 365 user account lockouts within a short 5-minute window. A high number of IdsLocked login errors across multiple user accounts may indicate brute-force attempts for the same users resulting in lockouts.
M365 Identity User Brute Force Attempted
Identifies brute-force authentication activity targeting Microsoft 365 user accounts using failed sign-in patterns that match password spraying, credential stuffing, or password guessing behavior. Adversaries may attempt brute-force authentication with credentials obtained from previous breaches, leaks, marketplaces or guessable passwords.
M365 OneDrive Malware File Upload
Identifies the occurrence of files uploaded to OneDrive being detected as Malware by the file scanning engine. Attackers can use File Sharing and Organization Repositories to spread laterally within the company and amplify their access. Users can inadvertently share these files without knowing their maliciousness, giving adversaries an opportunity to gain initial access to other endpoints in the environment.
M365 OneDrive/SharePoint Excessive File Downloads
Identifies when an excessive number of files are downloaded from OneDrive or SharePoint by an authorized user or application in a short period of time. This may indicate a potential data exfiltration event, especially if the downloads are performed using OAuth authentication which could suggest an OAuth phishing attack such as Device Code Authentication phishing.
M365 or Entra ID Identity Sign-in from a Suspicious Source
This rule correlate Entra-ID or Microsoft 365 mail successful sign-in events with network security alerts by source address. Adversaries may trigger some network security alerts such as reputation or other anomalies before accessing cloud resources.