Sudden spike in outbound email volume

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	1 Hour
Deduplication Period	2 Hours
Required Data	Microsoft 365 Emails
Detection Modules	Email
ATT&CK Tactic	Execution (TA0002), Credential Access (TA0006)
ATT&CK Technique	User Execution (T1204), Brute Force: Password Cracking (T1110.002)
Severity	Informational

Description

Unusual amount of emails sent by an internal sender to one or more external recipients within a short timeframe.

Attacker's Goals

• Extracting valuable information outside the company.
• Bypass Data Loss Prevention (DLP) by splitting data across multiple emails.

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

Sudden spike in outbound emails sent to external recipients

Synopsis

Field	Value
ATT&CK Tactic	Execution (TA0002), Credential Access (TA0006)
ATT&CK Technique	User Execution (T1204), Brute Force: Password Cracking (T1110.002)
Severity	Informational

Description

Unusual amount of emails sent by an internal sender to one or more external recipients within a short timeframe.

Attacker's Goals

• Extracting valuable information outside the company.
• Bypass Data Loss Prevention (DLP) by splitting data across multiple emails.

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.

Sudden spike in outbound emails sent to internal recipients

Synopsis

Field	Value
ATT&CK Tactic	Execution (TA0002), Credential Access (TA0006)
ATT&CK Technique	User Execution (T1204), Brute Force: Password Cracking (T1110.002)
Severity	Informational

Description

Unusual amount of emails sent by an internal sender to one or more external recipients within a short timeframe.

Attacker's Goals

• Extracting valuable information outside the company.
• Bypass Data Loss Prevention (DLP) by splitting data across multiple emails.

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.