EXPLORE DETECTIONS
O365 Multiple Failed MFA Requests For User
The following analytic identifies potential "MFA fatigue" attacks targeting Office 365 users by detecting more than nine Multi-Factor Authentication (MFA) prompts within a 10-minute timeframe. It leverages O365 management activity logs, focusing on Azure Active Directory events with the UserLoginFailed operation, a Success ResultStatus, and an ErrorNumber of 500121. This activity is significant as attackers may exploit MFA fatigue to gain unauthorized access by overwhelming users with repeated MFA requests. If confirmed malicious, this could lead to data breaches, unauthorized data access, or further compromise within the O365 environment. Immediate investigation is crucial.
O365 Multiple Mailboxes Accessed via API
The following analytic detects when a high number of Office 365 Exchange mailboxes are accessed via API (Microsoft Graph API or Exchange Web Services) within a short timeframe. It leverages 'MailItemsAccessed' operations in Exchange, using AppId and regex to identify API interactions. This activity is significant as it may indicate unauthorized mass email access, potentially signaling data exfiltration or account compromise. If confirmed malicious, attackers could gain access to sensitive information, leading to data breaches and further exploitation of compromised accounts. The threshold is set to flag over five unique mailboxes accessed within 10 minutes, but should be tailored to your environment.
O365 Multiple OS Vendors Authenticating From User
The following analytic identifies when multiple operating systems are used to authenticate to Azure/EntraID/Office 365 by the same user account over a short period of time. This activity could be indicative of attackers enumerating various logon capabilities of Azure/EntraID/Office 365 and attempting to discover weaknesses in the organizational MFA or conditional access configurations. Usage of the tools like "MFASweep" will trigger this detection.
O365 Multiple Service Principals Created by SP
The following analytic identifies instances where a single service principal creates more than three unique OAuth applications within a 10-minute timeframe. It leverages O365 logs from the Unified Audit Log, focusing on the 'Add service principal' operation in the Office 365 Azure Active Directory environment. This activity is significant as it may indicate a compromised or malicious service principal attempting to expand control or access within the network. If confirmed malicious, this could lead to unauthorized access and potential lateral movement within the environment, posing a significant security risk.
O365 Multiple Service Principals Created by User
The following analytic identifies instances where a single user creates more than three unique OAuth applications within a 10-minute window in the Office 365 environment. It leverages O365 logs from the Unified Audit Log, focusing on the 'Add service principal' operation in Azure Active Directory. This activity is significant as it may indicate a compromised user account or unauthorized actions, potentially leading to broader network infiltration or privilege escalation. If confirmed malicious, this behavior could allow attackers to gain persistent access, escalate privileges, or exfiltrate sensitive information.
O365 Multiple Users Failing To Authenticate From Ip
The following analytic identifies instances where more than 10 unique user accounts fail to authenticate from a single IP address within a 5-minute window. This detection leverages O365 audit logs, specifically Azure Active Directory login failures (AzureActiveDirectoryStsLogon). Such activity is significant as it may indicate brute-force attacks or password spraying attempts. If confirmed malicious, this behavior suggests an external entity is attempting to breach security by targeting multiple accounts, potentially leading to unauthorized access. Immediate action is required to block or monitor the suspicious IP and notify affected users to enhance their security measures.
O365 New Email Forwarding Rule Created
The following analytic identifies the creation of new email forwarding rules in an Office 365 environment. It detects events logged under New-InboxRule and Set-InboxRule operations within the o365_management_activity data source, focusing on parameters like ForwardTo, ForwardAsAttachmentTo, and RedirectTo. This activity is significant as unauthorized email forwarding can lead to data exfiltration and unauthorized access to sensitive information. If confirmed malicious, attackers could intercept and redirect emails, potentially compromising confidential communications and leading to data breaches.
O365 New Email Forwarding Rule Enabled
The following analytic identifies the creation of new email forwarding rules in an Office 365 environment via the UpdateInboxRules operation. It leverages Office 365 management activity events to detect rules that forward emails to external recipients by examining the OperationProperties for specific forwarding actions. This activity is significant as it may indicate unauthorized email redirection, potentially leading to data exfiltration. If confirmed malicious, attackers could intercept sensitive communications, leading to data breaches and information leakage.
O365 New Federated Domain Added
The following analytic identifies the addition of a new federated domain in an Office 365 environment. This behavior is detected by analyzing Office 365 management activity logs, specifically filtering for Workload=Exchange and Operation="Add-FederatedDomain". The addition of a new federated domain is significant as it may indicate unauthorized changes or potential compromises. If confirmed malicious, attackers could establish a backdoor, bypass security measures, or exfiltrate data, leading to data breaches and unauthorized access to sensitive information. Immediate investigation is required to review the details of the added domain and any concurrent suspicious activities.
O365 New Forwarding Mailflow Rule Created
The following analytic detects the creation of new mail flow rules in Office 365 that may redirect or copy emails to unauthorized or external addresses. It leverages Office 365 Management Activity logs, specifically querying for the "New-TransportRule" operation and parameters like "BlindCopyTo", "CopyTo", and "RedirectMessageTo". This activity is significant as it can indicate potential data exfiltration or unauthorized access to sensitive information. If confirmed malicious, attackers could intercept or redirect email communications, leading to data breaches or information leakage.
O365 New MFA Method Registered
The following analytic detects the registration of a new Multi-Factor Authentication (MFA) method for a user account within Office 365. It leverages O365 audit logs to identify changes in MFA configurations. This activity is significant as it may indicate an attacker's attempt to maintain persistence on a compromised account. If confirmed malicious, the attacker could bypass existing security measures, solidify their access, and potentially escalate privileges or access sensitive data. Immediate verification and remediation are required to secure the affected account.
O365 OAuth App Mailbox Access via EWS
The following analytic detects when emails are accessed in Office 365 Exchange via Exchange Web Services (EWS) using OAuth-authenticated applications. It leverages the ClientInfoString field to identify EWS interactions and aggregates metrics such as access counts, timing, and client IP addresses, categorized by user, ClientAppId, OperationCount, and AppId. Monitoring OAuth applications accessing emails through EWS is crucial for identifying potential abuse or unauthorized data access. If confirmed malicious, this activity could lead to unauthorized email access, data exfiltration, or further compromise of sensitive information.
O365 OAuth App Mailbox Access via Graph API
The following analytic detects when emails are accessed in Office 365 Exchange via the Microsoft Graph API using the client ID '00000003-0000-0000-c000-000000000000'. It leverages the 'MailItemsAccessed' operation within the Exchange workload, focusing on OAuth-authenticated applications. This activity is significant as unauthorized access to emails can lead to data breaches and information theft. If confirmed malicious, attackers could exfiltrate sensitive information, compromise user accounts, and further infiltrate the organization's network.
O365 Privileged Graph API Permission Assigned
The following analytic detects the assignment of critical Graph API permissions in Azure AD using the O365 Unified Audit Log. It focuses on permissions such as Application.ReadWrite.All, AppRoleAssignment.ReadWrite.All, and RoleManagement.ReadWrite.Directory. The detection method leverages Azure Active Directory workload events, specifically 'Update application' operations. This activity is significant as these permissions provide extensive control over Azure AD settings, posing a high risk if misused. If confirmed malicious, this could allow unauthorized modifications, leading to potential data breaches or privilege escalation. Immediate investigation is crucial.
O365 Privileged Role Assigned
The following analytic identifies the assignment of sensitive and privileged Azure Active Directory roles to an Azure AD user. Adversaries and red teams alike may assign these roles to a compromised account to establish Persistence in an Azure AD environment. This detection leverages the O365 Universal Audit Log data source.
O365 Privileged Role Assigned To Service Principal
The following analytic detects potential privilege escalation threats in Azure Active Directory (AD). This detection is important because it identifies instances where privileged roles that hold elevated permissions are assigned to service principals. This prevents unauthorized access or malicious activities, which occur when these non-human entities access Azure resources to exploit them. False positives might occur since administrators can legitimately assign privileged roles to service principals. This detection leverages the O365 Universal Audit Log data source.
O365 PST export alert
The following analytic detects instances where a user has initiated an eDiscovery search or exported a PST file in an Office 365 environment. It leverages Office 365 management activity logs, specifically filtering for events under ThreatManagement with the name "eDiscovery search started or exported." This activity is significant as it may indicate data exfiltration attempts or unauthorized access to sensitive information. If confirmed malicious, it suggests an attacker or insider threat is attempting to gather or exfiltrate data, potentially leading to data breaches, loss of intellectual property, or unauthorized access to confidential communications. Immediate investigation is required.
O365 Safe Links Detection
The following analytic detects when any Microsoft Safe Links alerting is triggered. This behavior may indicate when user has interacted with a phishing or otherwise malicious link within the Microsoft Office ecosystem.
O365 Security And Compliance Alert Triggered
The following analytic identifies alerts triggered by the Office 365 Security and Compliance Center, indicating potential threats or policy violations. It leverages data from the `o365_management_activity` dataset, focusing on events where the workload is SecurityComplianceCenter and the operation is AlertTriggered. This activity is significant as it highlights security and compliance issues within the O365 environment, which are crucial for maintaining organizational security. If confirmed malicious, these alerts could indicate attempts to breach security policies, leading to unauthorized access, data exfiltration, or other malicious activities.
O365 Service Principal New Client Credentials
The following analytic detects the addition of new credentials for Service Principals within an Office 365 tenant. It uses O365 audit logs, focusing on events related to credential modifications or additions in the AzureActiveDirectory workload. This activity is significant because Service Principals represent application identities, and their credentials allow applications to authenticate and access resources. If an attacker successfully adds or modifies these credentials, they can impersonate the application, leading to unauthorized data access, data exfiltration, or malicious operations under the application's identity.
O365 Service Principal Privilege Escalation
This detection identifies when an Azure Service Principal elevates privileges by adding themself to a new app role assignment.
O365 SharePoint Allowed Domains Policy Changed
The following analytic identifies when the allowed domain settings for O365 SharePoint have been changed. With Azure AD B2B collaboration, users and administrators can invite external users to collaborate with internal users. External guest account invitations may also need access to OneDrive/SharePoint resources. These changed should be monitored by security teams as they could potentially lead to unauthorized access.
O365 SharePoint Malware Detection
The following analytic identifies when a malicious file is detected within the SharePoint Online ecosystem. Attackers may stage and execute malicious files from within the Microsoft Office 365 ecosystem. Any detections from built-in Office 365 capabilities should be monitored and responded to appropriately. Certain premium Office 365 capabilities further enhance these detection and response functions.
O365 SharePoint Suspicious Search Behavior
The following analytic identifies when Office 365 users search for suspicious keywords or have an excessive number of queries to a SharePoint site within a limited timeframe. This behavior may indicate that a malicious actor has gained control of a user account and is conducting discovery or enumeration activities.