Potential spoofing of internal domain spotted

Cortex XDR Analytics Alert Reference by Alert name

Product
Cortex XDR
Last date published
2026-03-10
Category
Analytics Alert Reference
Index by
Alert name

Synopsis

Activation Period

14 Days

Training Period

30 Days

Test Period

N/A (single event)

Deduplication Period

1 Day

Required Data

  • Requires:
    • Microsoft 365 Emails

Detection Modules

Email

Detector Tags

Employee Impersonation, Spear Phishing

ATT&CK Tactic

ATT&CK Technique

Severity

Informational

Description

An external sender is possibly impersonating an employee by spoofing the company's internal address.

Attacker's Goals

  • Get credentials for internal systems.
  • Executing financial transfers from the company to the attacker's account.
  • Extracting information outside the company.
  • Encrypting critical information and demanding a ransom.

Investigative actions

  • Check the received header path, especially the sender host.
  • Check DMARC, SPF AND DKIM authentication results.
  • Verify whether the sender's IP address has appeared in different log sources before and its reputation.
  • If the message contains attachments or links, scrutinize them for any suspicious indications.
  • Monitor further actions taken, such as file downloads or access to potentially malicious links.