Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
234 detections
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Detects anomalous, high-volume activity in cloud-based services such as SharePoint, OneDrive, and Exchange, specifically tracking file access, downloads, and mailbox exports. This behavior may indicate bulk data collection, unauthorized exfiltration, or malicious data staging by a compromised account.
The following analytic identifies when an O365 email account sends an excessive number of email attachments to external recipients within a short period (within 1 hour).
This behavior may indicate a compromised account where the threat actor is attempting to exfiltrate data from the mailbox.
Threat actors may attempt to transfer data through email as a simple means of exfiltration from the compromised mailbox.
Some account owner legitimate behaviors can trigger this alert, however these actions may not be aligned with organizational expectations / best practice behaviors.
This behavior may indicate a compromised account where the threat actor is attempting to exfiltrate data from the mailbox.
Threat actors may attempt to transfer data through email as a simple means of exfiltration from the compromised mailbox.
Some account owner legitimate behaviors can trigger this alert, however these actions may not be aligned with organizational expectations / best practice behaviors.
Detects potential abuse of the Microsoft Graph API by correlating device-code authentication events with subsequent high-volume activity, such as mail or file enumeration, from the same account within a short window. This pattern is indicative of ARToken-style token proxying, where an attacker intercepts an OAuth device-code token to gain unauthorized access to an user's resources.
Detects a high volume of 'MailItemsAccessed' operations within a short 15-minute window performed by a specific application ID. This behavior is often indicative of automated, bulk exfiltration of emails from a Microsoft 365 environment, potentially by a compromised application or an attacker using a malicious OAuth application.
Detects newly consented OAuth applications that immediately perform mass access or exfiltration of mail and file data across multiple mailboxes or drives within a short period, potentially indicating an attacker utilizing a malicious OAuth application.
Detects Microsoft 365 Exchange MailItemsAccessed operations performed by a specific ClientAppId and AppId known to be associated with an exfiltration toolkit. This activity indicates unauthorized access to mail items, consistent with data harvesting efforts.
Detects high-frequency access to mail items via specific client applications, or high-frequency file downloads/access within SharePoint and OneDrive. These patterns may indicate suspicious data collection or exfiltration attempts by a compromised account.
Detects instances where browser extensions, potentially AI-assisted (e.g., Claude, Gemini), trigger automated mail actions (send, forward, summarize) to non-standard, external domains. This behavior may indicate an unauthorized agent attempting to exfiltrate or manipulate email content.
Detects a single host or account interacting with a high volume of archive (PST/OST) and document files, or initiating mailbox exports within a short window, which is often indicative of mass data staging and collection prior to exfiltration.
Detects suspicious O365 'MailItemsAccessed' activity using a specific OAuth application (AppId c999ed3e-27ae-4cb3-b3a2-46b056af63d3) and ClientId (5d661950-3475-41cd-a2c3-d671a3162bc1) with an 'Bind' operation type. This pattern is often associated with unauthorized email access across multiple tenant accounts. The rule triggers when at least 5 events are detected across 2 or more distinct tenant accounts within a 1-minute window, using a specific Firefox user agent.
Detects malicious manipulation of browser-based AI agents where process command-line arguments indicate an attempt to instruct the agent to access, summarize, and exfiltrate email messages from a user's webmail account.
This rule detects unauthorized mailbox access by identifying specific ClientAppId and API ID pairs known to be associated with an Office 365 email exfiltration toolkit. This activity is indicative of an attacker attempting to programmatically access or exfiltrate sensitive email data from the organization's environment.
Detects anomalous, high-volume access to email items by specific applications known to be associated with suspicious activity or unusual access patterns within the Exchange environment, potentially indicating email harvesting or data exfiltration.
Detects rapid access to multiple Microsoft 365 collection applications (Office, OneDrive, Teams) by a user account from specific AWS EC2 IP ranges identified as associated with the TeamFiltration tool. This behavior is consistent with automated exfiltration of email, chats, and files.
Detects high-frequency, automated polling of Microsoft 365 mailbox data via the Microsoft Graph API, characteristic of malicious inbox scanning tools (e.g., Box Monitor). The rule correlates these persistent access patterns with subsequent searches for high-value financial keywords, identifying potential Business Email Compromise (BEC) reconnaissance.
This rule detects potentially unauthorized access to Microsoft Graph API resources (Mail or Files) following a device-code authentication event for the same user. It identifies scenarios where a previously unknown application client performs read operations within 24 hours of a device-code login, which is characteristic of 'ARToken' or 'EvilProxy' type device-code phishing and session proxy attacks.
Detects high-volume, potentially automated data access, collection, or staging activities within Microsoft 365 services (SharePoint, OneDrive, and Exchange). The rule flags user identities performing a high count of operations (downloads, accesses, deletions, or export requests) across a wide range of unique objects or sites within a one-hour window, which is indicative of post-compromise mass data collection or exfiltration preparation.
This rule detects high-volume interactions with the Exchange Online REST API originated from the 'One Outlook Web' application ID, specifically filtering for events with associated token IDs. This pattern may indicate automated mailbox data exfiltration or unauthorized bulk email access, which has been observed in recent phishing-based identity compromise campaigns.
Detects high-volume, automated access and download activity targeting sensitive data within Microsoft 365 services (SharePoint, OneDrive, and Exchange) using the Microsoft Graph API. The rule identifies suspicious patterns of URI access associated with file downloading and mail item access, which may indicate automated data exfiltration by an adversary using compromised credentials or OAuth tokens.
Detects a sequence of events starting with a user signing in via the OAuth device code flow, followed immediately by mailbox item enumeration and sending of email. This pattern is characteristic of attackers who use device code phishing to steal tokens, subsequently using those tokens to access mailboxes and send malicious emails from the compromised account.
Detects anomalous access to email items containing financial keywords (e.g., payroll, invoice, banking) via 'MailItemsAccessed' events, characteristic of potential data collection following an AiTM (Adversary-in-the-Middle) account takeover. The rule identifies accounts accessing multiple financial emails without performing traditional BEC indicators such as creating inbox rules, modifying mailbox forwarding, or sending outbound phishing emails, which helps isolate silent exfiltration attempts.
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