| ID | Name |
|---|---|
| T1137.001 | Office Template Macros |
| T1137.002 | Office Test |
| T1137.003 | Outlook Forms |
| T1137.004 | Outlook Home Page |
| T1137.005 | Outlook Rules |
| T1137.006 | Add-ins |
Adversaries may abuse Microsoft Outlook's Home Page feature to obtain persistence on a compromised system. Outlook Home Page is a legacy feature used to customize the presentation of Outlook folders. This feature allows for an internal or external URL to be loaded and presented whenever a folder is opened. A malicious HTML page can be crafted that will execute code when loaded by Outlook Home Page.[1]
Once malicious home pages have been added to the user’s mailbox, they will be loaded when Outlook is started. Malicious Home Pages will execute when the right Outlook folder is loaded/reloaded.[1]
| ID | Name | Description |
|---|---|---|
| G0049 | OilRig |
OilRig has abused the Outlook Home Page feature for persistence. OilRig has also used CVE-2017-11774 to roll back the initial patch designed to protect against Home Page abuse.[2] |
| S0358 | Ruler |
Ruler can be used to automate the abuse of Outlook Home Pages to establish persistence.[3] |
| ID | Mitigation | Description |
|---|---|---|
| M1040 | Behavior Prevention on Endpoint |
On Windows 10, enable Attack Surface Reduction (ASR) rules to prevent Office applications from creating child processes and from writing potentially malicious executable content to disk. [4] |
| M1051 | Update Software |
For the Outlook methods, blocking macros may be ineffective as the Visual Basic engine used for these features is separate from the macro scripting engine.[5] Microsoft has released patches to try to address each issue. Ensure KB3191938 which blocks Outlook Visual Basic and displays a malicious code warning, KB4011091 which disables custom forms by default, and KB4011162 which removes the legacy Home Page feature, are applied to systems.[1] |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0177 | Detect Persistence via Outlook Home Page Exploitation | AN0502 |
Adversary uses a tool like Ruler to configure a malicious Outlook folder Home Page that loads a remote or embedded HTML payload upon folder interaction. Execution chain begins with Outlook launching, a specific folder being accessed, and a suspicious child process being spawned or COM-based execution invoked. |
| AN0503 |
Malicious HTML or script is rendered as a Home Page for a specific Outlook folder. Outlook accesses that folder, loads remote content, and executes embedded JavaScript or ActiveX/COM logic resulting in unauthorized actions or local execution. |