What is rundll32.exe

If you use a Windows machine, no doubt you’re familiar with the three-finger shuffle – control-alt-delete, invented funnily enough by another David Bradley. This no longer reboots your PC, but brings up Windows Task Manager (you can also use Ctrl-Shift-Esc to do the same). You’ve probably seen all kinds of entries in the processes list in Task Manager such as “svchost.exe”, “jusched.exe”, and “ctfmon.exe” and a few more familiar entries pertaining to the software you’re running and I’ve explained them elsewhere on this blog. But, what on earth is rundll32.exe?

rundll32.exe is an internal program used by Windows to run yet other internal programs known as DLLs (dynamic link libraries) which are needed by the operating system and your programs (Word, Outlook, Internet Explorer, OpenOffice, Thunderbird, Firefox, or whatever to function). It loads up the DLL into memory and then triggers specific functions from the DLL module.

To see what else is running on your machine and what programs are using them you might like to try Sysinternal’s Process Explorer, which was recently acquired by Micro$oft and is available for free download here.