Analytics BIOC Informational
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Email attachment with multiple extensions

The email includes an attachment(s) with two extensions. The first one being an executable extension. This may indicate an attempt at masquerading the true file type through the misuse of multiple extensions in the attachment name.

Module:
Email Security
Licensed by:
Email Security
Data source:
Microsoft 365 Emails
ATT&CK tactics: Execution (TA0002) Defense Evasion (TA0005)
ATT&CK techniques: User Execution: Malicious File (T1204.002) Masquerading: Double File Extension (T1036.007)
Attacker's goals:

Trick users into interacting with malicious attachments that seem legitimate. Deploy malicious attachments through emails to compromise systems or gain unauthorized access.

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 or missing letters. Verify the sender's address to confirm its legitimacy. Check for previous emails from the sender's address.

Test period:
N/A (single event)
Deduplication:
1 Hour 30 Minutes
2 variations:
  • Email executable attachment with multiple extensions Low (parent: Informational)
  • Email executable attachment with multiple executable extensions Low (parent: Informational)