Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
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This query was originally published in the threat analytics report, Qakbot blight lingers, seeds ransomware
Qakbot is malware that steals login credentials from banking and financial services. It has been deployed against small businesses as well as major corporations. Some outbreaks have involved targeted ransomware campaigns that use a similar set of techniques. Links to related queries are listed under See also.
The following query detects attempts to access files in the local path that contain Outlook emails.
Reference - https://www.microsoft.com/security/blog/2017/11/06/mitigating-and-eliminating-info-stealing-qakbot-and-emotet-in-corporate-networks/
Qakbot is malware that steals login credentials from banking and financial services. It has been deployed against small businesses as well as major corporations. Some outbreaks have involved targeted ransomware campaigns that use a similar set of techniques. Links to related queries are listed under See also.
The following query detects attempts to access files in the local path that contain Outlook emails.
Reference - https://www.microsoft.com/security/blog/2017/11/06/mitigating-and-eliminating-info-stealing-qakbot-and-emotet-in-corporate-networks/
Count of all Senders and where they were delivered
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 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.
This analytic identifies when an Office 365 email recipient receives and then deletes emails related to both password changes and banking/payroll changes within a short period. This behavior may indicate a compromised account where a threat actor is attempting to redirect the victim's payroll to an attacker-controlled bank account. The rule correlates message trace logs with management activity logs to detect the receipt and subsequent deletion of specific types of emails.
The following analytic identifies when an O365 email recipient receives and then deletes emails related to password or banking/payroll changes within a short period. This behavior may indicate a compromised account where the threat actor is attempting to redirect the victims payroll to an attacker controlled bank account.
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 analytic identifies hosts receiving an unusually high volume of network traffic from an email server. It leverages the Network_Traffic data model to sum incoming bytes to clients from email servers, comparing current traffic against historical averages and standard deviations. This activity is significant as it may indicate data exfiltration by a malicious actor using the email server. If confirmed malicious, this could lead to unauthorized data access and potential data breaches, compromising sensitive information and impacting organizational security.
The following analytic identifies instances where read permissions are assigned to mailbox folders within an Office 365 environment. It leverages the `o365_management_activity` data source, specifically monitoring the `ModifyFolderPermissions` and `AddFolderPermissions` operations, while excluding Calendar, Contacts, and PersonMetadata objects. This activity is significant as unauthorized read permissions can lead to data exposure and potential information leakage. If confirmed malicious, an attacker could gain unauthorized access to sensitive emails, leading to data breaches and compromising the confidentiality of organizational communications.
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.
The following analytic identifies instances where read permissions are granted to mailbox folders within an Office 365 environment. It detects this activity by monitoring the `o365_management_activity` data source for the `Set-MailboxFolderPermission` and `Add-MailboxFolderPermission` operations. This behavior is significant as it may indicate unauthorized access or changes to mailbox folder permissions, potentially exposing sensitive email content. If confirmed malicious, an attacker could gain unauthorized access to read email communications, leading to data breaches or information leakage.
This rule identifies API requests made to the Microsoft Graph API to access user mailboxes and retrieve a specified number of messages. It specifically looks for GET requests to the `/v1.0/users/*/mailFolders/*/messages?$top=` endpoint with a successful HTTP 200 response. This activity could indicate an attacker attempting to exfiltrate emails from a compromised mailbox.
Identify when mailboxes are being accessed with requests for N number of messages
Detect mail items accessed via API through an unapproved Entra ID application.
This rule detects when a user performs an eDiscovery search or exports a PST file from such a search within Microsoft 365. PST files often contain sensitive information, including email body content, making this activity a potential indicator of data exfiltration or unauthorized access to sensitive communications.
Detects the use of PowerShell to add Exchange snap-ins and potentially export mailbox data. This activity has been observed in attacks by threat groups such as HAFNIUM and APT27, often as part of post-exploitation to collect sensitive information from Exchange servers.
Detects PowerShell scripts attempting to access the default Windows Mail App mailbox data. This activity could indicate an adversary trying to manipulate, exfiltrate, or delete stored emails. The detection specifically looks for the string '\Comms\Unistore\data' within PowerShell script blocks, which points to the location where the Windows Mail App stores its data.
Alert when a user has performed an export to a search using 'New-ComplianceSearchAction' with the '-Export' flag. This detection will detect PST export even if the 'eDiscovery search or exported' alert is disabled in the O365. This rule will apply to ExchangePowerShell usage and from the cloud.
Detects the usage of the PowerShell `Set-Mailbox` cmdlet to configure an SMTP forwarding rule for a mailbox. This can be indicative of an adversary setting up automatic email forwarding to an external address for data exfiltration or continued access to communications.
Alert on when a user has performed an eDiscovery search or exported a PST file from the search. This PST file usually has sensitive information including email body content
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