Analytics BIOC Informational
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Email attachment with a potentially malicious file extension

The email message includes attachments with file types that are typically blocked by the email vendor as a precaution due to their suspicious nature.

Module:
Email Security
Licensed by:
Email Security
Data source:
Microsoft 365 Emails
ATT&CK tactics: Initial Access (TA0001) Execution (TA0002)
ATT&CK techniques: Phishing (T1566) User Execution (T1204)
Attacker's goals:

Trick users into clicking on malicious attachments Deploy malicious attachments through emails to compromise systems, gain unauthorized access, or facilitate cyber threats.

Investigative actions:

Check the file types and investigate the legitimacy of files intended to be sent via email. Scrutinize the attachments for any suspicious indications. Confirm whether the attachments were successfully delivered to the recipient's mailbox. If the attachments were delivered successfully, verify whether the recipient downloaded them. Check the email address for any unusual spellings. Check the email address for any missing letters. Verify the sender's domain to confirm its legitimacy. Examine the sender's IP address and reputation. Verify whether the sender's IP address has appeared in different log sources before. Verify if the sender's IP address is identifiable.

Test period:
N/A (single event)
Deduplication:
1 Hour 30 Minutes
2 variations:
  • Attachment(s) with a potentially malicious file extension unusual for the organization Informational
  • Attachment(s) with a potentially malicious file extension unusual for the recipient Informational