rundll32.exe is used to run some other 32-bit applets and dynamic link
libraries (DLLs) and it is that applet. possibly malicious, that is
wanting to access the net not rundll32.exe.

The version tag on most legitimate files usually provides enough
information as to the files purpose and origin. Using that and perhaps
Google it shouldn't take more than a few moments to understand in simple
terms its purpose. To know more, how long have you got?

Let's take rundll32.exe as an example. The version tab tells me "Run a
DLL as an App", That is, run a Dynamic Link Library as an Application, in
other words just like a file with an exe extension. DLLs can't be run in
isolation. They usually contain common functions used by other DLLs and
applications, in other words a library. What rundll32.exe does is allow
certain DLLs to be launched without there being a parent application.
--
Mike Maltby MS-MVP



psynapse wrote:

I have an EZ firewall that keeps asking me if rundll32.exe
application can have permission to access the internet. A
few questions: a) what IS a rundll32? b) should it access
the internet and c) why?

As a user rather than a computer expert, I just want the
thing to work! So why is it these applications all have
incomprehensible names and no explaination when I open up
their properties files? Wouldn't it be great if each had a
little file that opened with it and told you such things
as a) what it is meant to do, b) who to contact when it
goes wrong, etc. You know, customer friendly information?