Mach2

Mach2 manages the Windows Feature Store, where Features (and associated on/off state) live. This store lives in the undocumented Windows Notification Facility (WNF), which provides publish-subscribe messaging for kernel components, system services, and user-space applications.

Windows currently contains thousands of Feature switches that turn on and off new and unfinished functionality, mitigations, test hooks, and overrides. Mach2 provides facilities to discover these switches and turn them on or off.

Without going into specifics, Mach2 commands generally fall into one of two buckets: Scanning

Mach2 operates on Feature IDs for the bulk of its operations. But finding interesting Features to turn on and off can be a chore, so it includes a scanning function. This function scans Microsoft Program Database (PDB) files for Feature symbols and collects them for review. A user can then review the results and cherry pick which Features warrant further investigation. Management

Mach2 can dump the current Feature Control store and resolve known IDs to names for convienence. (It reads simple key:value pairs from features.txt on disk.)

With a Feature ID in hand, Mach2 can enable or disable a Feature on the local system. Both of these actions create configuration state for the Feature and set the feature to Enabled or Disabled respectively. The user can also choose to Revert back to the default configuration -- that is, let the Feature turn itself on or off as desired. (There is a Default configuration state that could be set, the tool currently opts to remove reverted features from the configuration store altogether.)

While the tool can manipulate Feature states, the Feature itself drives state compliance. That is, it can choose to ignore its configured state. Various factors, including what's referred to internally as a staging configuration, can dictate whether a Feature respects its configurable state or not. (Always Disabled staged Features, for example, are crippled/stripped during Windows build compilation and cannot be turned on with Feature Control.)