First-seen email from mailbox owner to external recipient's address in the last 30 days

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	N/A (single event)
Deduplication Period	1 Day
Required Data	Microsoft 365 Emails
Detection Modules	Email
Detector Tags	Exfiltration, Account Takeover
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Informational

Description

Internal sender initiated first-time communication with an external recipient in the last 30 days.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.

Variations

First-time email to the disposable domain

Synopsis

Field	Value
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Low

Description

Internal sender emailed to external address(es) with disposable domain.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.

First-time email from organization's domain with the external recipient's domain in the last 30 days

Synopsis

Field	Value
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Informational

Description

Internal sender emailed an external address belonging to a domain seen for the first time by the organization domain in the last 30 days.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.

First-time email from organization with the external recipient in the last 30 days

Synopsis

Field	Value
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Informational

Description

Internal sender emailed to external address(es) that first-seen by the the whole organization in the last 30 days.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.

First-time email from organization's domain to the external recipient in the last 30 days

Synopsis

Field	Value
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Informational

Description

Internal sender emailed to external address(es) that first-seen by the organization domain in the last 30 days.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.

First-time email from mailbox owner to the external recipient's domain in the last 30 days

Synopsis

Field	Value
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Informational

Description

Internal sender emailed to external address(es) with domain that first-seen by that sender in the last 30 days.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.

First-time outbound email from mailbox owner to multiple external recipients without any internal recipients in the last 30 days

Synopsis

Field	Value
ATT&CK Tactic	Exfiltration (TA0010)
ATT&CK Technique	Exfiltration Over Alternative Protocol (T1048)
Severity	Informational

Description

Internal sender emailed first-time to multiple external recipients with no internal recipients included in the last 30 days.

Attacker's Goals

• Extracting valuable information outside the company.

Investigative actions

• Check the content of the email that was sent.
• Review the external recipient address and assess its reputation.
• Review past emails sent from this mailbox for any suspicious activity.
• Check for unusual emails sent to this recipient's address.
• Monitor further action taken, such as accessing to private keys, API tokens and sensitive data.