External email display name impersonation of internal personnel

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	N/A (single event)
Deduplication Period	1 Hour 30 Minutes
Required Data	Microsoft 365 Emails
Detection Modules	Email
Detector Tags	Employee Impersonation, Spear Phishing
ATT&CK Tactic	Stealth (TA0005)
ATT&CK Technique	Social Engineering: Impersonation (T1684.001)
Severity	Informational

Description

Potential email attempting to impersonate an internal user has been detected.

• The sender's email address appears unusual in relation to the provided display name, suggesting a possible impersonation attempt targeting an internal user.

Attacker's Goals

Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.

Investigative actions

• Check the email address for any unusual spellings, missing letters, or unknown domains.
• Examine the sender's IP address and reputation.
• Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
• 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.

Variations

External email display name impersonation of internal personnel, using a public provider

Synopsis

Field	Value
ATT&CK Tactic	Stealth (TA0005)
ATT&CK Technique	Social Engineering: Impersonation (T1684.001)
Severity	Informational

Description

Potential email attempting to impersonate an internal user has been detected.

• The sender's email address appears unusual in relation to the provided display name, suggesting a possible impersonation attempt targeting an internal user.

Attacker's Goals

Impersonate internal users or familiar individuals and trick them into clicking on malicious links or attachments.

Investigative actions

• Check the email address for any unusual spellings, missing letters, or unknown domains.
• Examine the sender's IP address and reputation.
• Verify whether the sender's IP address has appeared in different log sources before, and if it is recognizable.
• 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.