Account Discovery: Email Account

Adversaries may attempt to get a listing of email addresses and accounts. Adversaries may try to dump Exchange address lists such as global address lists (GALs).[1]

In on-premises Exchange and Exchange Online, theGet-GlobalAddressList PowerShell cmdlet can be used to obtain email addresses and accounts from a domain using an authenticated session.[2][3]

In Google Workspace, the GAL is shared with Microsoft Outlook users through the Google Workspace Sync for Microsoft Outlook (GWSMO) service. Additionally, the Google Workspace Directory allows for users to get a listing of other users within the organization.[4]

ID: T1087.003
Sub-technique of:  T1087
Tactic: Discovery
Platforms: Google Workspace, Office 365, Windows
Permissions Required: User
Data Sources: Command: Command Execution, User Account: User Account Metadata
Version: 1.1
Created: 21 February 2020
Last Modified: 31 March 2021

Procedure Examples

ID Name Description
S0093 Backdoor.Oldrea

Backdoor.Oldrea collects address book information from Outlook.[5]

S0367 Emotet

Emotet has been observed leveraging a module that can scrape email addresses from Outlook.[6][7]

S0531 Grandoreiro

Grandoreiro can parse Outlook .pst files to extract e-mail addresses.[8]

S0413 MailSniper

MailSniper can be used to obtain account names from Exchange and Office 365 using the Get-GlobalAddressList cmdlet.[3]

S0358 Ruler

Ruler can be used to enumerate Exchange users and dump the GAL.[9]

G0034 Sandworm Team

Sandworm Team used malware to enumerate email settings, including usernames and passwords, from the M.E.Doc application.[10]

G0092 TA505

TA505 has used the tool EmailStealer to steal and send lists of e-mail addresses to a remote server.[11]

S0266 TrickBot

TrickBot collects email addresses from Outlook.[12]

Mitigations

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Detection

System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as Lateral Movement, based on the information obtained.

Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

References