Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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This query helps reviewing user reported email submissions
This query helps reviewing status of submissions
This query helps reviewing top 100 senders in your organization in last 30 days
This query helps getting GeoIP information of emails SenderIPv4 addresses.
This query helps in reviewing malicious emails allowed due to user overrides
This query helps reviewing top submitters of user submissions
This query helps reviewing top submitters of admin submissions
Identify emails that were send from an address external to your company and where email was send to more then 50 distinct corporate users.
Update corporatedomain.com to your corporate domain to have it excluded.
Update 50 if you want to adjust the distinct user count.
Update corporatedomain.com to your corporate domain to have it excluded.
Update 50 if you want to adjust the distinct user count.
Count of recipient's email addresses by subject
Count of all Senders and where they were delivered
This rule detects a significant increase in undeliverable emails for a specific user within a short timeframe. This pattern can indicate that a user's account has been compromised and is being used to send out a large volume of phishing or spam emails, leading to many bounce-back messages. It could also suggest a targeted phishing campaign where the sender's email address is being spoofed, and the legitimate user is receiving the undeliverable notifications.
This analytic identifies the creation or modification of email inbox rules within an Office 365 environment. It specifically looks for `New-InboxRule` and `Set-InboxRule` operations in the O365 management activity logs where the rule parameters indicate actions such as mail forwarding (`ForwardTo`, `ForwardAsAttachmentTo`, `RedirectTo`), or mail manipulation like deletion (`SoftDeleteMessage`, `DeleteMessage`) or moving to specific folders (`MoveToFolder`, `CopyToFolder`). While legitimate users create inbox rules, adversaries often leverage these techniques to exfiltrate emails, maintain persistence, or hide their activities by deleting or moving security alerts.
This analytic identifies when an O365 email account sends an email and then hard deletes email within a short period (within 1 hour). This behavior may indicate a compromised account where the threat actor is attempting to remove forensic artifacts or evidence of activity. Threat actors often use this technique to prevent defenders and victims from knowing the account has been compromised.
The following analytic identifies instances where email forwarding has been enabled on mailboxes within an Office 365 environment. It detects this activity by monitoring the Set-Mailbox operation within the o365_management_activity logs, specifically looking for changes to the ForwardingAddress or ForwardingSmtpAddress parameters. 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.
The following analytic identifies when Office 365 users search for suspicious keywords or have an excessive number of queries to a mailbox within a limited timeframe. This behavior may indicate that a malicious actor has gained control of a mailbox and is conducting discovery or enumeration activities.
The following analytic identifies when an O365 email account hard deletes an excessive number of emails within a short period (within 1 hour). This behavior may indicate a compromised account where the threat actor is attempting to permanently purge a large amount of items from the mailbox. Threat actors may attempt to remove evidence of their activity by purging items 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 analytic identifies when built-in Microsoft 365 security detections for suspicious email behaviors are triggered. These alerts often indicate that an attacker may have compromised a mailbox within the environment, leading to activities such as suspicious email sending patterns, user restrictions from sending email, suspicious email forwarding activity, or email sending limits being exceeded. Monitoring these alerts is crucial for responding to potential account compromises and malicious email activities.
The following analytic detects outbound emails with attachments sent from an internal email domain to an external domain. It leverages Gsuite Gmail logs, parsing the source and destination email domains, and flags emails with fewer than 20 outbound instances. This activity is significant as it may indicate potential data exfiltration or insider threats. If confirmed malicious, an attacker could use this method to exfiltrate sensitive information, leading to data breaches and compliance violations.
This rule detects the creation of new mail flow rules in Office 365 that are configured to redirect or copy emails to unauthorized or external addresses. It specifically looks for the "New-TransportRule" operation in Office 365 Management Activity logs, combined with parameters such as "BlindCopyTo", "CopyTo", or "RedirectMessageTo". Such activity can indicate potential data exfiltration, unauthorized access to sensitive information, or an attacker attempting to intercept email communications, which could lead to data breaches or information leakage.
The following analytic detects instances where the inbox folder of an Office 365 mailbox is shared with all users within the tenant. It leverages Office 365 management activity events to identify when the 'Inbox' folder permissions are modified to include 'Everyone' with read rights. This activity is significant as it represents a potential security risk, allowing unauthorized access to sensitive emails. If confirmed malicious, this could lead to data breaches, exfiltration of confidential information, and further compromise through spear-phishing or other malicious activities based on the accessed email content.
The following analytic identifies when an O365 email account sends and then hard deletes an email to an external recipient within a short period (within 1 hour). This behavior may indicate a compromised account where the threat actor is attempting to remove forensic artifacts or evidence of exfiltration activity. This behavior is often seen when threat actors want to reduce the probability of detection by the compromised account owner.
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