Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
149 detections
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Detects high-volume or multi-mailbox activity in Exchange Online, indicative of automated mailbox collection or unauthorized bulk data access via Graph or REST APIs. The rule monitors for a threshold of operations across multiple mailboxes or high event counts originating from specific API clients.
Detects the creation of email inbox rules in Microsoft 365 where the rule name is exceptionally short ('.' or '..') and the rule performs potentially malicious actions such as forwarding, redirecting, or deleting incoming messages. This is a common technique used by attackers to hide malicious email activity or exfiltrate sensitive data from a compromised account.
This rule detects potentially unauthorized mailbox content exports within Microsoft 365, including the creation of mailbox export requests, PST-related compliance searches, and the downloading of exported search results. These activities are common precursors to data exfiltration.
Detects browser activity where a user agent navigates to common webmail services (Gmail, Outlook) followed quickly by network traffic to potentially malicious external infrastructure or non-standard endpoints, suggesting unauthorized email content exfiltration.
Detects browser activity where a user agent navigates to common webmail services (Gmail, Outlook) followed quickly by network traffic to potentially malicious external infrastructure or non-standard endpoints, suggesting unauthorized email content exfiltration.
Detects browser activity where a user agent navigates to common webmail services (Gmail, Outlook) followed quickly by network traffic to potentially malicious external infrastructure or non-standard endpoints, suggesting unauthorized email content exfiltration.
Detects automated mailbox access operations such as 'MailItemsAccessed' or 'Search-Mailbox' that are filtered by specific, high-risk financial or Business Email Compromise (BEC) keywords in the email subject line. This behavior is indicative of an automated 'inbox-monitor' style attack, where a compromised OAuth token is used to systematically scrape mailboxes for sensitive financial data.
Detects anomalous access to sensitive Microsoft Graph API endpoints (messages, mailFolders, contacts) following a device-code authentication. The rule specifically flags activity from non-standard or generic client applications, which is a pattern often associated with post-compromise proxying or token abuse, such as the 'ARToken' technique.
Detects DNS resolution attempts for graph.microsoft.com by processes other than standard web browsers or mail clients. This activity is indicative of scripted tools or malicious software attempting to enumerate or access Microsoft 365 mailbox content via the Graph API, bypassing normal user interaction.
Detects anomalous, high-frequency mailbox search and access activity targeting financial-related keywords (e.g., invoices, wire transfers, bank details). This behavior pattern is frequently observed during business email compromise (BEC) attacks, where adversaries utilize OAuth tokens to triage mailboxes for sensitive payment information.
Detects high-frequency requests to Microsoft Graph API endpoints related to messages, mailFolders, or attachments, indicative of an adversary performing mailbox reconnaissance or data collection via cloud APIs.
Detects anomalous or high-volume activity related to Microsoft Graph API calls targeting email messages, mail folders, or attachments. This behavior is indicative of potential unauthorized bulk email collection or exfiltration attempts, often observed in account compromise scenarios where an attacker enumerates and downloads mail contents.
Detects anomalous or high-volume activity related to Microsoft Graph API calls targeting email messages, mail folders, or attachments. This behavior is indicative of potential unauthorized bulk email collection or exfiltration attempts, often observed in account compromise scenarios where an attacker enumerates and downloads mail contents.
Detects high-frequency access to mail items or attachments using specific One Outlook Web Client AppIDs. This behavior may indicate automated mailbox harvesting or unauthorized bulk data access via an atypical API path.
Detects a new client secret added to an Entra ID application shortly followed by Mail.ReadWrite Graph API calls, indicating the application was hijacked to impersonate its identity and read a target user's mailbox — the technique CISA's red team used after obtaining an access token.
Detects anomalous mailbox access via the MailItemsAccessed operation, specifically identifying the unique ClientAppId and API pairing associated with the Storm-2755 (Payroll Pirates) adversary campaign. This activity indicates unauthorized access to email content, typically targeting high-value personnel such as payroll, finance, and HR staff through Adversary-in-the-Middle (AiTM) techniques.
Detects bursts of 10+ MailItemsAccessed events within 60 seconds via a REST client with a specific ClientAppId/APIId pairing, consistent with automated mailbox collection using a replayed AiTM-stolen session token.
Detects centralized automation collecting mail across 3+ tenants within a short synchronized window, consistent with coordinated mailbox collection infrastructure.
This rule detects potential mass email access or collection activities by an application (AppId). It monitors Microsoft 365 CloudAppEvents for actions like 'MailItemsAccessed', 'Send', or 'New-InboxRule' associated with an application. It triggers an alert when a single application interacts with 10 or more distinct mailboxes within a one-hour window, which is indicative of potential Business Email Compromise (BEC) or unauthorized mass data exfiltration via compromised OAuth applications.
This rule detects potential mass email access or collection activities by an application (AppId). It monitors Microsoft 365 CloudAppEvents for actions like 'MailItemsAccessed', 'Send', or 'New-InboxRule' associated with an application. It triggers an alert when a single application interacts with 10 or more distinct mailboxes within a one-hour window, which is indicative of potential Business Email Compromise (BEC) or unauthorized mass data exfiltration via compromised OAuth applications.
Detects Microsoft Graph API requests targeting user mailboxes within a tenant or organization structure likely associated with Israeli legal entities, identified by .co.il domain patterns in the Request URI.
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