T1114.002: Remote Email Collection

Adversaries may target an Exchange server, Office 365, or Google Workspace to collect sensitive information. Adversaries may leverage a user's credentials and interact directly with the Exchange server to acquire information from within a network. Adversaries may also access externally facing Exchange services, Office 365, or Google Workspace to access email using credentials or access tokens. Tools such as MailSniper can be used to automate searches for specific keywords.

Positive Technologies products that cover the technique

MaxPatrol SIEM knowledge base

microsoft_exchange: PT-CR-494: Exchange_PST_upload_via_Administrator: Attempt to upload PST files via Exchange shell and delete information about it microsoft_exchange: PT-CR-2763: Exchange_ActiveSync_Emails_Access_via_PEAS: Downloading the contents of the mailbox of a user, whose credentials were previously obtained, by using the Microsoft ActiveSync function for synchronization with the Exchange mail server

Detection

IDDS0017Data source and componentCommand: Command ExecutionDescription

Monitor executed commands and arguments for actions that may target an Exchange server, Office 365, or Google Workspace to collect sensitive information.

IDDS0029Data source and componentNetwork Traffic: Network Connection CreationDescription

Monitor for newly constructed network connections that are sent or received by untrusted hosts.

IDDS0015Data source and componentApplication Log: Application Log ContentDescription

In Office365 environments, consider using PurviewAudit to collect MailItemsAccessed events and monitoring for unusual email access behavior.

IDDS0028Data source and componentLogon Session: Logon Session CreationDescription

Monitor for unusual login activity from unknown or abnormal locations, especially for privileged accounts (ex: Exchange administrator account).

Mitigation

IDM1041NameEncrypt Sensitive InformationDescription

Use of encryption provides an added layer of security to sensitive information sent over email. Encryption using public key cryptography requires the adversary to obtain the private certificate along with an encryption key to decrypt messages.

IDM1032NameMulti-factor AuthenticationDescription

Use of multi-factor authentication for public-facing webmail servers is a recommended best practice to minimize the usefulness of usernames and passwords to adversaries.