# System Binary Proxy Execution: MMC

Adversaries may abuse mmc.exe to proxy execution of malicious .msc files. Microsoft Management Console (MMC) is a binary that may be signed by Microsoft and is used in several ways in either its GUI or in a command prompt.[1][2] MMC can be used to create, open, and save custom consoles that contain administrative tools created by Microsoft, called snap-ins. These snap-ins may be used to manage Windows systems locally or remotely. MMC can also be used to open Microsoft created .msc files to manage system configuration.[3]

For example, mmc C:\Users\foo\admintools.msc /a will open a custom, saved console msc file in author mode.[1] Another common example is mmc gpedit.msc, which will open the Group Policy Editor application window.

Adversaries may use MMC commands to perform malicious tasks. For example, mmc wbadmin.msc delete catalog -quiet deletes the backup catalog on the system (i.e. Inhibit System Recovery) without prompts to the user (Note: wbadmin.msc may only be present by default on Windows Server operating systems).[4][5]

Adversaries may also abuse MMC to execute malicious .msc files. For example, adversaries may first create a malicious registry Class Identifier (CLSID) subkey, which uniquely identifies a Component Object Model class object.[6] Then, adversaries may create custom consoles with the "Link to Web Address" snap-in that is linked to the malicious CLSID subkey.[7] Once the .msc file is saved, adversaries may invoke the malicious CLSID payload with the following command: mmc.exe -Embedding C:\path\to\test.msc.[8]

ID: T1218.014
Sub-technique of:  T1218
Tactic: Defense Evasion
Platforms: Windows
Defense Bypassed: Application control, Digital Certificate Validation
Contributors: Wes Hurd
Version: 2.0
Created: 28 September 2021

## Mitigations

ID Mitigation Description
M1042 Disable or Remove Feature or Program

MMC may not be necessary within a given environment since it is primarily used by system administrators, not regular users or clients.

M1038 Execution Prevention

Use application control configured to block execution of MMC if it is not required for a given system or network to prevent potential misuse by adversaries.

## Detection

ID Data Source Data Component Detects
DS0017 Command Command Execution

Monitor executed commands and arguments that may gather information about the victim's DNS that can be used during targeting.

DS0022 File File Creation

Monitor for creation and use of .msc files. MMC may legitimately be used to call Microsoft-created .msc files, such as services.msc or eventvwr.msc. Invoking non-Microsoft .msc files may be an indicator of malicious activity.

DS0009 Process Process Creation

Monitor processes for suspicious or malicious use of MMC. Since MMC is a signed Windows binary, verify use of MMC is legitimate and not malicious.