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A few years ago I saw somebody play a prank on somebody by associating the .exe file extension with Internet Explorer. This made Internet Explorer open up every time the person wanted to start a program.
Unfortunately, I forgot how this was done. I tried to use the Default Programs > Set Associations Control Panel tool, but it didn't list .exe.
How could one set this file association, and, perhaps more importantly, how could one unset it?
When doing "pranks" like that, it is not enough to just follow a step-by-step tutorial or a batch script; it's best to know something about how the actual data is stored – it becomes easier to recover later.
All file associations are kept in Registry, which can be edited using regedit or reg. The shell looks for them under HKEY_CLASSES_ROOT, which is a merged view of HKEY_LOCAL_MACHINE\Software\Classes (system-wide) and HKEY_CURRENT_USER\Software\Classes (user-local).
HKEY_CLASS_ROOT ]
.txt ]
txtfile " – pointer to another key under HKCRtxtfile ]
Text Document " – textual description as displayed in Explorershell ] – the actions to use for double-click and context-menu
open"open ]
Open"command ]
%SystemRoot%\system32\NOTEPAD.EXE %1 "For most extensions, the HKCR\.extn\(Default) value points to a file type key under the same HKCR; for example, .exe points to HKCR\exefile.
(In rare cases, though, all information is under the extension's key directly, with HKCR\.extn\(Default) containing the description. These seem to be very rare, though – maybe a leftover of Windows 9x or 3.x...)
Make backups. reg save HKLM\Software\Classes hklm-classes.hiv Also, remember that the Command Prompt does not care about extensions; if you try to run an executable program, it will always run no matter how it is named, or what its extension is associated with.
reg save takes care of that (and also includes metadata, which reg export would skip).
– grawity
Nov 7 '11 at 14:35
FTYPE and ASSOC commands, and the file type list is also accessible via dialogue boxes in Windows Explorer directly.
– JdeBP
Nov 7 '11 at 14:38
regedit gives a nice overview.
– grawity
Nov 7 '11 at 14:41
Try this:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\.exe]
@="exefile"
"Content Type"="application/x-msdownload"
[HKEY_CLASSES_ROOT\.exe\PersistentHandler]
@="{098f2470-bae0-11cd-b579-08002b30bfeb}"
