Cross-source coverage
T1137.003 / ATT&CK
Office Application Startup: Outlook Forms
1 rule across 1 source.
From MITRE ATT&CK 19.2
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.
- Tactics
- Persistence
- Platforms
- Windows · Office Suite
- Telemetry
-
WinEventLog:SysmonWinEventLog:ApplicationWinEventLog:PowerShellm365:unifiedm365:messagetrace
How MITRE says to detect it DET0029
Detect Persistence via Outlook Custom Forms Triggered by Malicious Email
Windows Analytic 0085
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.
WinEventLog:SysmonEventCode=1WinEventLog:SysmonEventCode=7WinEventLog:ApplicationOutlook errors loading or processing custom form templatesWinEventLog:PowerShellExecution of Microsoft script to enumerate custom forms in Outlook mailbox
Office Suite Analytic 0086
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.
m365:unifiedUnusual form activity within Outlook client, including load of non-default formsm365:messagetraceInbound email triggers execution of mailbox-stored custom form
SigmaHQ/sigma
1 rule| Detection | Severity | Format |
|---|---|---|
| Potential Persistence Via Outlook Form | High | Sigma |