C# – How to start a new process without administrator privileges from a process with administrator privileges

administratorcwindows

I am creating an automatic updater for an application. The application is started by the user, and runs without administrator privileges. The autoupdater is started with administrator privileges, and kills the application before it downloads the new files.

The problem comes when I want to start the updated application after the autoupdater is finished. If I use regular System.Diagnostics.Process.Start(file), the application starts with administrator privileges too, and it has to run on the current user to work as intended.

So, how can I make the autoupdater start the application as the current user instead of the administrator?

I have tried using the following:

var pSI = new ProcessStartInfo() { 
    UseShellExecute = false, 
    UserName = Environment.UserName, 
    FileName = file 
};
System.Diagnostics.Process.Start(pSI);

But this throws the error "Invalid user name or password". I have checked that the username is correct, and I understand that the password probably is invalid, as I have not included it. But it is not an option to ask the user to input his/her password, since the entire reason to start the application automatically is to make it easier for the user.

Any suggestions?

Best Answer

What you are trying to achieve cannot be done very easily and is not supported. However, it is possible using a modicum of hacking. Aaron Margosis wrote an article describing one technique.

To quote the pertinent section, you will need to carry out these steps:

Enable the SeIncreaseQuotaPrivilege in your current token

Get an HWND representing the desktop shell (GetShellWindow)

Get the Process ID (PID) of the process associated with that window (GetWindowThreadProcessId)

Open that process (OpenProcess)

Get the access token from that process (OpenProcessToken)

Make a primary token with that token (DuplicateTokenEx)

Start the new process with that primary token (CreateProcessWithTokenW)

The article contains a download link for some demo C++ source from which it should be simple enough to translate to C#.

New answer, powershell

TCP

Get-Process -Id (Get-NetTCPConnection -LocalPort YourPortNumberHere).OwningProcess

UDP

Get-Process -Id (Get-NetUDPEndpoint -LocalPort YourPortNumberHere).OwningProcess

Old answer, cmd

 C:\> netstat -a -b

(Add -n to stop it trying to resolve hostnames, which will make it a lot faster.)

Note Dane's recommendation for TCPView. It looks very useful!

-a Displays all connections and listening ports.

-b Displays the executable involved in creating each connection or listening port. In some cases well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case the executable name is in [] at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.

-n Displays addresses and port numbers in numerical form.

-o Displays the owning process ID associated with each connection.

C# – How to create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office

You can use a library called ExcelLibrary. It's a free, open source library posted on Google Code:

ExcelLibrary

This looks to be a port of the PHP ExcelWriter that you mentioned above. It will not write to the new .xlsx format yet, but they are working on adding that functionality in.

It's very simple, small and easy to use. Plus it has a DataSetHelper that lets you use DataSets and DataTables to easily work with Excel data.

ExcelLibrary seems to still only work for the older Excel format (.xls files), but may be adding support in the future for newer 2007/2010 formats.

You can also use EPPlus, which works only for Excel 2007/2010 format files (.xlsx files). There's also NPOI which works with both.

There are a few known bugs with each library as noted in the comments. In all, EPPlus seems to be the best choice as time goes on. It seems to be more actively updated and documented as well.

Also, as noted by @АртёмЦарионов below, EPPlus has support for Pivot Tables and ExcelLibrary may have some support (Pivot table issue in ExcelLibrary)

Here are a couple links for quick reference:
ExcelLibrary - GNU Lesser GPL
EPPlus - GNU (LGPL) - No longer maintained
EPPlus 5 - Polyform Noncommercial - Starting May 2020
NPOI - Apache License

Here some example code for ExcelLibrary:

Here is an example taking data from a database and creating a workbook from it. Note that the ExcelLibrary code is the single line at the bottom:

//Create the data set and table
DataSet ds = new DataSet("New_DataSet");
DataTable dt = new DataTable("New_DataTable");

//Set the locale for each
ds.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;
dt.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;

//Open a DB connection (in this example with OleDB)
OleDbConnection con = new OleDbConnection(dbConnectionString);
con.Open();

//Create a query and fill the data table with the data from the DB
string sql = "SELECT Whatever FROM MyDBTable;";
OleDbCommand cmd = new OleDbCommand(sql, con);
OleDbDataAdapter adptr = new OleDbDataAdapter();

adptr.SelectCommand = cmd;
adptr.Fill(dt);
con.Close();

//Add the table to the data set
ds.Tables.Add(dt);

//Here's the easy part. Create the Excel worksheet from the data set
ExcelLibrary.DataSetHelper.CreateWorkbook("MyExcelFile.xls", ds);

Creating the Excel file is as easy as that. You can also manually create Excel files, but the above functionality is what really impressed me.

Best Answer

Related Solutions

Windows – How to you find out which process is listening on a TCP or UDP port on Windows

New answer, powershell

TCP

UDP

Old answer, cmd

C# – How to create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office

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