The OpenSaveMRU key exists in the Windows Registry and tracks files that have been opened or saved within a Windows shell dialog box. It is part of a set of keys recording information from the Windows Common Dialog. The Common Dialog libraries can be used by any Windows application and Microsoft highly recommends that developers use them instead of creating novel user interface elements.
Data is commonly found in this key from web browsers, document viewers, archiving utilities, and image viewers.
Registry Key Location
The key is present in each user's NTUSER.DAT hive in the \Software\Microsoft\Windows\CurrentVersion\Explorer\ComDIg32\OpenSaveMRU location. The values stored in the key itself are items that do not have file extensions associated with them.
Since most files in Windows have extensions, what often ends up here is auto-complete information. Consider an OpenSave dialog box that allows you to choose a file type from a list (e.g. .jpg, .png, .bmp). User input into this dialog will typically be the name of the file without the extension, since the dropdown filetype menu takes care of filling in the extension. Thus what will be stored in the OpenSaveMRU value is auto-complete information for that transaction, and the full filename is not stored.
The possibility for a large number of subkeys exist within the OpenSaveMRU key. All but one of the sub-keys correspond to file extensions and store full path information for files of that extension that have been opened or saved. Each subkey keeps its own Most Recently Used (MRU) list and last write time.
One outlier is the * subkey. This key tracks the last ten files of any extension (including no extension) that have been input into the OpenSave dialog.
OpenSaveMRU in Windows 7
Starting with Windows Vista, the key has been renamed to OpenSavePidlMRU
- Harlan Carvey, Windows Forensic Analysis DVD Toolkit, 2009