Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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Detects bulk IMAP email collection from remote mail servers
This rule detects potential bulk email collection activity over IMAP. It triggers when a client makes 30 or more IMAP 'FETCH' commands containing 'BODY[]' (indicating a request for the full email body) to a server on port 143 within a 60-second window. This behavior can be indicative of an attacker or malicious insider exfiltrating a large number of emails from an IMAP server.
This rule detects a high volume of HTTP requests to graph.microsoft.com with the URI containing '/messages', indicating a potential bulk download of emails from Office 365 via the Graph API. The threshold is set to 30 requests within 60 seconds from a single source IP.
Identifies a risky sign-in to a known O365 landing page followed shortly by the creation of an inbox rule that deletes messages or moves them to junk/trash. This pattern frequently indicates account compromise (e.g., BEC or AiTM) attempting to hide malicious activity.
This rule detects potential email harvesting attempts via Exchange Web Services (EWS). It specifically looks for HTTP requests to the '/EWS/Exchange.asmx' endpoint containing 'FindItem' in the client body, indicating an attempt to enumerate or search for items (like emails) within mailboxes. A threshold is applied to prevent excessive alerts from legitimate, but frequent, EWS activity.
This rule detects the creation or modification of Exchange transport rules or inbox rules that forward or redirect emails to external domains. It specifically looks for operations like 'New-TransportRule', 'Set-TransportRule', 'New-InboxRule', 'Set-InboxRule', 'Set-Mailbox', 'UpdateInboxRules', and 'Set-TransportConfig' where the destination is an email address outside of the organization's verified domains. This activity can indicate data exfiltration or an attempt to maintain persistence and collect sensitive information.
Detects the explicit loading of the Exchange Management snap-in by PowerShell, often a precursor to mailbox exfiltration as seen in SHADOW-EARTH-053 activity. This activity can indicate an adversary is preparing to interact with Exchange mailboxes.
MC1293480: https://admin.cloud.microsoft/?ref=MessageCenter/:/messages/MC1293480
Detects early-stage collection and reconnaissance activities targeting sensitive email data prior to exfiltration via Exchange cmdlets. This rule identifies the use of 'New-MailboxSearch' and 'Get-Recipient' cmdlets, which can be leveraged by adversaries to discover and collect email-related information. Detection covers both endpoint PowerShell execution and cloud audit logs for Microsoft Exchange Online.
Detects access to the Zimbra mailbox export endpoint (/home/~/?fmt=tgz). This native Zimbra feature is actively abused by APT actors (such as in Operation GhostMail) to silently export emails without deploying custom collection tools.
This rule detects chat or call activity by external users in Microsoft Teams whose source tenant is not present in a pre-defined whitelist. This could indicate unauthorized external communication or potential data exfiltration attempts.
Purpose: Hunts for risky OAuth applications in Microsoft 365 with overly permissive Microsoft Graph permissions.
Key Actions:
Finds enabled OAuth apps and retrieves their latest state (arg_max).
Expands permissions and flags sensitive ones (e.g., Mail.Send, Files.ReadWrite.All, User.ReadWrite.All, Sites.ReadWrite.All).
Notes publisher verification, origin, and last modification date.
Marks risky apps via HasRiskyPermissions flag.
Use Cases: Detects malicious consent grant phishing, overprivileged third-party apps, and integrations that could enable data theft or long-term access.
Key Actions:
Finds enabled OAuth apps and retrieves their latest state (arg_max).
Expands permissions and flags sensitive ones (e.g., Mail.Send, Files.ReadWrite.All, User.ReadWrite.All, Sites.ReadWrite.All).
Notes publisher verification, origin, and last modification date.
Marks risky apps via HasRiskyPermissions flag.
Use Cases: Detects malicious consent grant phishing, overprivileged third-party apps, and integrations that could enable data theft or long-term access.
KQL Query from file: Threat hunting voice phishing for Teams
KQL Query from file: Exposure Management + Defender for Office 365
KQL Query from file: MDO Email Threat Classification By ISP
KQL Query from file: MDO Email Threat Classification By Country
KQL Query
'Looks for new device registrations following a risky user account sign-in. By default the
query will use a 6 hour lookback period, this can be configured within the query.'
query will use a 6 hour lookback period, this can be configured within the query.'
This query looks for anomalies in mail item access events made by Graph API. It uses standard deviation to determine if the number of events is anomalous. The query returns all clientIDs where the amount of mail sent per day was larger than value given by the formula, 'average + STDThreshold(2.5)*(standard deviation)'.
See The MailItemsAccessed mailbox auditing action.
Reference - https://docs.microsoft.com/microsoft-365/compliance/mailitemsaccessed-forensics-investigations?view=o365-worldwide#the-mailitemsaccessed-mailbox-auditing-action
See The MailItemsAccessed mailbox auditing action.
Reference - https://docs.microsoft.com/microsoft-365/compliance/mailitemsaccessed-forensics-investigations?view=o365-worldwide#the-mailitemsaccessed-mailbox-auditing-action
Intent:
- Use MTP capability to look for insider threat potential risk indicators
- Indicators would then serve as the building block for insider threat risk modeling in subsequent tools
Definition of Insider Threat:
"The potential for an individual who has or had authorized access to an organization's assets to use their access, either maliciously or unintentionally, to act in a way that could negatively affect the organization."
This collection of queries describes the different indicators that could be used to model and look for patterns suggesting an increased risk of an individual becoming a potential insider threat.
Note: no single indicator should be used as a lone determinant of insider threat activity, but should be part of an overall program to understand the increased risk to your organization's critical assets. This in turn is used to feed an investigation by a formal insider threat program to look at the context associated with the whole person to understand the implication of a set of indicators.
- Use MTP capability to look for insider threat potential risk indicators
- Indicators would then serve as the building block for insider threat risk modeling in subsequent tools
Definition of Insider Threat:
"The potential for an individual who has or had authorized access to an organization's assets to use their access, either maliciously or unintentionally, to act in a way that could negatively affect the organization."
This collection of queries describes the different indicators that could be used to model and look for patterns suggesting an increased risk of an individual becoming a potential insider threat.
Note: no single indicator should be used as a lone determinant of insider threat activity, but should be part of an overall program to understand the increased risk to your organization's critical assets. This in turn is used to feed an investigation by a formal insider threat program to look at the context associated with the whole person to understand the implication of a set of indicators.
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