When writing applications, how can I determine the minimum required
privileges necessary for an operation to run?
For instance, say my application needs rights to write/read to the registry,
or I want to block some ports - how do I go about finding out what the
minimum privileges required are?  Is there a documentation somewhere that
says "function X requires privilege leve Y"?

Thanks!

Hello, SC!

S> When writing applications, how can I determine the minimum required
S> privileges necessary for an operation to run?
S> For instance, say my application needs rights to write/read to the
S> registry, or I want to block some ports - how do I go about finding out
S> what the minimum privileges required are?  Is there a documentation
S> somewhere that says "function X requires privilege leve Y"?

Generaly it is documented, what privilidges are sufficient to complete this or that operation.
However, most efficient method to detect what priviliedges your app requires - is running
your application under user account with least privileges.

Show quote Hide quote I wish it was. I have been looking in the MS docs for stuff like this and
have yet to find specifics about it.

Building and then running and then patching where needed seems to be a path
that is very contrary to structured design IMHO. Security should be part of
the design from the start, not tacked on to the end. Testing should be used
to validate not design.

Hello, Ray!
You wrote  on Fri, 1 Sep 2006 11:54:05 -0400:

RCH> I wish it was. I have been looking in the MS docs for stuff like this
and
RCH> have yet to find specifics about it.

IMO it depends what are you trying to do. For instance if you want to do
disk I/O...
File.Open docs have following statement:

"FileIOPermission  for reading from and writing to the specified file.
Associated enumerations: FileIOPermissionAccess.Read,
FileIOPermissionAccess.Write"
Also you should consider the existance of ACLs
File.Open uses CreateFile win32 API, this function has
lpSecurityAttributes parametr and MSDN gives comments about it.

RCH> Building and then running and then patching where needed seems to be a
path
RCH> that is very contrary to structured design IMHO. Security should be
part of
RCH> the design from the start, not tacked on to the end.

Yes, I agree with you about that.
But OP asked about OS priveleges to accomplish (reading registry)
some operations. These privileges must be either documented in docs
or if user works under least privileges she will get an error (Access
denied).

When you design your own system you define YOUR
own system priviliges. This privileges are part of the design.

I my post I meant to do the development and testing under least privilidged
user
account, since it will help to detect priviledge related issues from the
start.
( http://dotnetjunkies.com/WebLog/anoras/archive/2005/02/14/54376.aspx )

Do you mean CAS permissions or operating system permissions?  If the former,
what version of the .NET framework are you targeting?


Show quoteHide quote

OS permissions

Show quoteHide quote

For ACL-based stuff (files, registry, etc.), you can p/invoke the
AccessCheck or AzAccessCheck API calls, depending on if you have a logon
token for the user you want to check against.  Unfortunately, there is no
built in .NET wrapper for these yet.

For network stuff, I'm not sure if there is a well-known API to determine
the network requirements of any given call.  I think you kind of need to
know this stuff in advance.

Joe K.

Show quoteHide quote

In .NET 2.0 you can use the Permission Calculator tool (permcalc)
[http://msdn2.microsoft.com/en-us/library/ms165077.aspx] after you have
written the app to see what permissions it needs.

There is no equivalent in .NET 1.0 or 1.1 unfortunately, but you can
run the 2.0 permcalc against a 1.* assembly and still see results.

There are some differences in the framework as to what permissions are
required however, for example the OdbcConnection in 1.* requires
fulltrust whereas in 2.0 it does not.  SqlConnection objects just need
SqlClientPermission in both.

It is an annoying process to add security after the fact, the best
reccomendation i've seen is to develop as a least permission user (VS
Debugger user etc) or to remove all default permissions with [assembly:
PermissionSet(SecurityAction.RequestOptional, Unrestricted=false)] up
front.

As you add functionality and it throws security exceptions run you can
research what permissions each object needs.

Hope this is useful

Merritt

SC wrote:
Show quoteHide quote

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