sigmamediumHunting

Potential Data Exfiltration Over SMTP Via Send-MailMessage Cmdlet

Detects the execution of a PowerShell script with a call to the "Send-MailMessage" cmdlet along with the "-Attachments" flag. This could be a potential sign of data exfiltration via Email. Adversaries may steal data by exfiltrating it over an un-encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

MITRE ATT&CK

T1048.003

exfiltration

Detection Query

selection:
  ScriptBlockText|contains: Send-MailMessage*-Attachments
condition: selection

Author

frack113

Created

2022-09-26

Data Sources

windowsps_script

Platforms

windows

References

Tags

attack.exfiltrationattack.t1048.003detection.threat-hunting

Raw Content

title: Potential Data Exfiltration Over SMTP Via Send-MailMessage Cmdlet
id: 9a7afa56-4762-43eb-807d-c3dc9ffe211b
status: test
description: |
    Detects the execution of a PowerShell script with a call to the "Send-MailMessage" cmdlet along with the "-Attachments" flag. This could be a potential sign of data exfiltration via Email.
    Adversaries may steal data by exfiltrating it over an un-encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1048.003/T1048.003.md#atomic-test-5---exfiltration-over-alternative-protocol---smtp
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/send-mailmessage?view=powershell-7.4
    - https://www.ietf.org/rfc/rfc2821.txt
author: frack113
date: 2022-09-26
modified: 2024-11-01
tags:
    - attack.exfiltration
    - attack.t1048.003
    - detection.threat-hunting
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains: 'Send-MailMessage*-Attachments'
    condition: selection
falsepositives:
    - Unknown
level: medium