MMC

What the technique is

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. 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. For example, mmc C:\Users\foo\admintools.msc /a will open a custom, saved console msc file in author mode. 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). 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. Then, adversaries may create custom consoles with the “Link to Web Address” snap-in that is linked to the malicious CLSID subkey. […]

What MITRE says you would watch

• AN0622

  Abuse of mmc.exe to execute non-Microsoft or user-staged.msc files and malicious COM CLSIDs. Behavioral chain: (1) suspicious mmc.exe invocation with /a or -Embedding and non-standard.msc path → (2) COM activation of non-baseline CLSIDs by mmc.exe → (3) mmc.exe loads non-baseline DLLs (user-writable/UNC/unsigned) → (4) optional network/DNS activity from mmc.exe.