Techniques › T1137.003 › AN0085
AN0085 Analytic 0085
Windows · attack.mitre.org · ATT&CK Enterprise v19.2
<p>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.</p>
- Detects
- T1137.003 Outlook Forms
- Part of
- DET0029 Detect Persistence via Outlook Custom Forms Triggered by Malicious Email
Log sources and channels
Exactly as MITRE states them in x_mitre_log_source_references. Where a channel is vague, it is vague in the source; kevmap does not tidy it.
| Log source | Channel | Data component |
|---|---|---|
| WinEventLog:Sysmon | EventCode=1 | DC0032 Process Creation |
| WinEventLog:Sysmon | EventCode=7 | DC0016 Module Load |
| WinEventLog:Application | Outlook errors loading or processing custom form templates | DC0038 Application Log Content |
| WinEventLog:PowerShell | Execution of Microsoft script to enumerate custom forms in Outlook mailbox | DC0064 Command Execution |
Mutable elements
Parameters MITRE marks as environment-specific. These are the knobs you are expected to tune; they are why an analytic is not a rule.
| Field | Description |
|---|---|
FormStorageLocation | Malicious forms may be stored in various user-specific locations in the Outlook mailbox (e.g., IPM.Note class) |
ChildProcessName | Child process spawned by outlook.exe may vary (e.g., powershell.exe, rundll32.exe, mshta.exe) |
TimeWindow | Form-triggered execution may happen immediately upon Outlook startup or with delay after crafted message arrival |
OutlookVersion | Form behavior and error logs may vary across Outlook 2013, 2016, and M365 builds |
UserContext | Attack may target only specific users; contextual correlation needed for account baselining |