Outlook Forms
Where this stands
One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
Adversaries may abuse Microsoft Outlook forms to obtain persistence on a compromised system. Outlook forms are used as templates for presentation and functionality in Outlook messages. Custom Outlook forms can be created that will execute code when a specifically crafted email is sent by an adversary utilizing the same custom Outlook form. Once malicious forms have been added to the user’s mailbox, they will be loaded when Outlook is started. Malicious forms will execute when an adversary sends a specifically crafted email to the user.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0085
Adversary uses a tool like Ruler to insert a malicious custom form into the user's Outlook mailbox. The form is designed to auto-execute on Outlook startup or on receipt of a specially crafted email. This results in child processes launched from outlook.exe and possibly network connections or payload loading.
- AN0086
Outlook form execution upon message receipt or client launch results in automated code execution within user session. Form definitions deviate from standard templates and include script logic or COM object calls embedded in form fields.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.