Suspicious Email Attachment Extensions: networkEndpoint2025-02-10version:7
The following analytic detects emails containing attachments with suspicious file extensions. It leverages the Email data model in Splunk, using the tstats command to identify emails where the attachment filename is not empty. This detection is significant for SOC analysts as it highlights potential phishing or malware delivery attempts, which are common vectors for data breaches and malware infections. If confirmed malicious, this activity could lead to unauthorized access to sensitive information, system compromise, or data exfiltration. Immediate review and analysis of the identified emails and attachments are crucial to mitigate these risks.
O365 ZAP Activity Detection: threatO365 Tenant2025-03-25version:6
The following analytic detects when the Microsoft Zero-hour Automatic Purge (ZAP) capability takes action against a user's mailbox. This capability is an enhanced protection feature that retro-actively removes email with known malicious content for user inboxes. Since this is a retroactive capability, there is still a window in which the user may fall victim to the malicious content.
Suspicious Email - UBA Anomaly: threatEndpoint2024-11-14version:6
This detection looks for emails that are suspicious because of their sender, domain rareness, or behavior differences. This is an anomaly generated by Splunk User Behavior Analytics (UBA).
Email Attachments With Lots Of Spaces: networkEndpoint2025-01-21version:5
The following analytic detects email attachments with an unusually high number of spaces in their file names, which is a common tactic used by attackers to obfuscate file extensions. It leverages the Email data model to identify attachments where the ratio of spaces to the total file name length exceeds 10%. This behavior is significant as it may indicate an attempt to bypass security filters and deliver malicious payloads. If confirmed malicious, this activity could lead to the execution of harmful code or unauthorized access to sensitive information within the recipient's environment.
O365 Threat Intelligence Suspicious Email Delivered: threatO365 Tenant2025-03-25version:6
The following analytic identifies when a suspicious email is detected within the Microsoft Office 365 ecosystem through the Advanced Threat Protection engine and delivered to an end user. Attackers may execute several attacks through email, any detections from built-in Office 365 capabilities should be monitored and responded to appropriately. Certain premium Office 365 capabilities such as Safe Attachment and Safe Links further enhance these detection and response functions.
O365 Email Send Attachments Excessive Volume: threatO365 Tenant2025-01-20version:1
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.
O365 Email Reported By User Found Malicious: threatO365 Tenant2025-03-25version:6
The following analytic detects when an email submitted to Microsoft using the built-in report button in Outlook is found to be malicious. This capability is an enhanced protection feature that can be used within o365 tenants by users to report potentially malicious emails. This correlation looks for any submission that returns a Phish or Malware verdict upon submission.
O365 Email Suspicious Behavior Alert: threatO365 Tenant2025-03-25version:6
The following analytic identifies when one of O365 the built-in security detections for suspicious email behaviors are triggered. These alerts often indicate that an attacker may have compromised a mailbox within the environment. Any detections from built-in Office 365 capabilities should be monitored and responded to appropriately. Certain premium Office 365 capabilities further enhance these detection and response functions.
O365 Email Reported By Admin Found Malicious: threatO365 Tenant2025-03-25version:6
The following analytic detects when an email manually submitted to Microsoft through the Security & Compliance portal is found to be malicious. This capability is an enhanced protection feature that can be used within o365 tenants by administrative users to report potentially malicious emails. This correlation looks for any submission that returns a Phish or Malware verdict upon submission.
Monitor Email For Brand Abuse: networkEndpoint2025-01-21version:5
The following analytic identifies emails claiming to be sent from a domain similar to one you are monitoring for potential abuse. It leverages email header data, specifically the sender's address, and cross-references it with a lookup table of known domain permutations generated by the "ESCU - DNSTwist Domain Names" search. This activity is significant as it can indicate phishing attempts or brand impersonation, which are common tactics used in social engineering attacks. If confirmed malicious, this could lead to unauthorized access, data theft, or reputational damage.
O365 Email Receive and Hard Delete Takeover Behavior: threatO365 Tenant2025-01-20version:1
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.
O365 Email Hard Delete Excessive Volume: threatO365 Tenant2025-01-20version:1
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.
O365 Email Send and Hard Delete Suspicious Behavior: threatO365 Tenant2025-01-20version:1
The following analytic identifies when an O365 email account sends and then hard deletes email with 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. --- Some account owner legitimate behaviors can trigger this alert, however these actions may not be aligned with organizational expectations / best practice behaviors.
O365 Email Send and Hard Delete Exfiltration Behavior: threatO365 Tenant2025-01-20version:1
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.
O365 Email Password and Payroll Compromise Behavior: threatO365 Tenant2025-01-20version:1
The following analytic identifies when an O365 email recipient receives and then deletes emails for the combination of both password and 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.
