T1672 Email Spoofing

Adversaries may fake, or spoof, a sender’s identity by modifying the value of relevant email headers in order to establish contact with victims under false pretenses.⁴ In addition to actual email content, email headers (such as the FROM header, which contains the email address of the sender) may also be modified. Email clients display these headers when emails appear in a victim’s inbox, which may cause modified emails to appear as if they were from the spoofed entity.

This behavior may succeed when the spoofed entity either does not enable or enforce identity authentication tools such as Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and/or Domain-based Message Authentication, Reporting and Conformance (DMARC).¹²⁵ Even if SPF and DKIM are configured properly, spoofing may still succeed when a domain sets a weak DMARC policy such as v=DMARC1; p=none; fo=1;. This means that while DMARC is technically present, email servers are not instructed to take any filtering action when emails fail authentication checks.⁴³

Adversaries may abuse Microsoft 365’s Direct Send functionality to spoof internal users by using internal devices like printers to send emails without authentication.⁶ Adversaries may also abuse absent or weakly configured SPF, SKIM, and/or DMARC policies to conceal social engineering attempts³ such as Phishing. They may also leverage email spoofing for Impersonation of legitimate external individuals and organizations, such as journalists and academics.³

Mitigations

References