is there a way in C# to see what credentials are used to access a file in a network share?
I'm trying to debug a scenario where most of CIS Windows L1 hardening settings are applied to a system. This system only has local users and one of them (a member of local Administrators group) is used to run a C# app (.NET Framework 4.7.2) that accesses a network share, say \\myserver\some\path\foo.xml. Without hardening, it all works fine, even though when I have a look at who can access the network share, the local user is not listed.
With hardening applied, it does not work. More concretely: in File Explorer, when trying to access the foo.xml, a CredUI prompt for credentials appears. I have to submit my own credentials (AD user) to get access.
What the app does is essentially
string[] possiblePaths = ... // load possible network paths of desired file
foreach (string possiblePath in possiblePaths)
{
if (File.Exists(possiblePath))
{
return possiblePath;
}
}
I figured out how to deal with the SeTcbPrivilege policy violation (that gave me errors in the Event Log), but after that, I am lost.
To debug, I have created a test app:
string path = #"\\myserver\some\path\foo.xml";
if (File.Exists(path))
{
Console.WriteLine($"Path {path} exists!");
}
else
{
Console.WriteLine($"Path {path} does not exist!");
}
try
{
var fh = File.Open(path, FileMode.Open);
fh.Close();
}
catch (Exception ex)
{
Console.WriteLine(ex);
Console.WriteLine(ex.Message);
if (ex.InnerException != null)
{
Console.WriteLine(ex.InnerException.Message);
}
}
When I restart the system and try to run the app without providing my credentials to File Explorer, it says "The path does not exist" and IOException that the network path does not exist. However, when I submit my own credentials (not the local user, but mine, as an AD user) in File Explorer to access that location, the output of the test app says "The path exists" and UnauthorizedAccessException: Access to the path ... is denied. Which is weird, as I don't run the app as me, but as the local user.
I know I can use trial-error (and probably will) to identify the policy messing it up, but I would like to constrain it as much as possible - and also to understand why exactly it is causing trouble (maybe there used to be some anonymous/guest access on the share that is not permitted now on the system?).
To that extent, I would very welcome any nudge as how to see what credentials a C# app is using to authenticate elsewhere, how to get more debug info, or how the File.Exists()/File.Open() work under the hood.
Thanks!
i am trying to return all the files contain in a folder in UWP application for Windows 10, the code is shown below:
var path = #"C:\Users\Desktop";
var files = System.IO.Directory.GetFiles(path); //get empty arrays
But, i get empty string arrays, may I know what causes this problem?
You can't. For uwp and store apps, only the app installation and app temp folders are granted for direct access. 'Direct' means ... accesses without Windows.Storge broker process. (System.IO is 'direct'.)
If you want to access the 'outside' of your app - like as desktop, you need to ask user to pick the location by File/FolderPicker. Without the user interaction, you can't access.
However, Windows.Storage broker service provide the rich methods for file operation, and additional functions like as CommnonQuery features.
There are some exception for pictures, video folders, but the basic concept is same.
Following link may helps you. :)
File access permissions
Probably because C:\Users\Desktop doesn't exist on the system - it would be under C:\Users\YOUR_USERNAME\Desktop.
Additionally, your application might be operating in a sandbox, so all filesystem access will be virtualized to a private silo elsewhere - Windows would pretend that the directory you specified exists but says it's empty, because it doesn't want you accessing the user's files without prior permission.
I deployed my internal web application to server A and got an error when creating a file to a network drive on server B. If I run locally, the file got created on server B successfully.
System.UnauthorizedAccessException: Access to the path '\\b\folder\test.pdf' is denied.
The identity of the application pool is networkservice. And I gave networkservice full control on the destination folder on server B. I even gave Everyone full control, but it still got the error.
Server A runs .NET 7.5. Code to create file:
var byteArray = generateArray();
var destination = "\\\\b\\folder\\test.pdf";
try {
var destinationFile = new FileInfo(destination);
if (destinationFile.Exists) {
destinationFile.Delete();
}
System.IO.File.WriteAllBytes(destination, byteArray);
} catch (UnauthorizedAccessException) {
//
}
I've seen someone got the exact same problem here. But it didn't solve mine.
Solution:
I changed the identity to administrator account instead of using network service for the application pool. It works but I don't fully understand why it works. Because the network service on A is different than the one on B?
Even though you provided access to everyone, certain applications have to receive specific permission. This was apart of the UAC System introduced in Window's Vista. This move was to increase security, so an application couldn't run under any user and basically have full access.
What you should do, is on the directory provide the following access:
IIS AppPool\NameOfAppPool
That will provide specific access to your hosted web application to that directory, for IIS will be able to correctly manipulate the directory. Some code you could implement to help validate before you write or read, would be:
public static bool ValidateIOPermission(string path)
{
try
{
if(Directory.Exist(path))
return true;
else { Directory.CreateDirectory(path); }
}
catch(Exception ex) { return false; }
}
The above code is a small sample, basically try to perform the action and catch the exception, that way you know if you have access or not.
I'm facing a weird issue, when trying to access file on SD card with code:
var path = #"D:\Test\test.txt";
try
{
StorageFile file = await StorageFile.GetFileFromPathAsync(path);
}
catch (Exception ex) { Debug.WriteLine($"File access failed due to {ex.Message}"); }
path = #"Test\test.txt";
StorageFile file2 = await (await KnownFolders.RemovableDevices.GetFoldersAsync()).FirstOrDefault().GetFileAsync(path);
The file is on SD card, I've declared RemovableStorage capability, and added FileTypeAssociation. I can get the file when I first debug the app, but on the second run I get UnauthorizedException with the first StorageFile. Amazingly the second try to get the file via RemovableStorage works every time.
If I only restart the phone and debug app once again - it will again work, but still only for the first time.
Is accessing files by StorageFile.GetFileFromPathAsync() somehow limited?
Am I missing something?
UPDATE:
Seems like on newest version of emulator 10856 I get an exception on every run, what may mean that there will be no way to access file via full path.
The picker allows access because the user provided the file to you, not the path. A winstore app should not be dependent upon a users drive / folder layout, that is why you don't have authority to access files by absolute path. In this case, we should firstly allow access to removable devices in manifest file, then we should use system's RemovebleDevices folder to access files of allowable types.
Also it is strange you can work with the absolute path the first time. In my test device, I always get the UnauthorizedAccessException and "Access is denied" error if using absolute path. My device is of build 10586.11.
I am having a problem where I am trying to delete my file but I get an exception.
if (result == "Success")
{
if (FileUpload.HasFile)
{
try
{
File.Delete(Request.PhysicalApplicationPath + app_settings.login_images + txtUploadStatus.Text);
string filename = Path.GetFileName(btnFileUpload.FileName);
btnFileUpload.SaveAs(Request.PhysicalApplicationPath + app_settings.login_images + filename);
}
catch (Exception ex)
{
Message(ex.ToString());
}
}
}
Also I should note that the folder I am trying to delete from has full control to network services.
The full exception message is:
System.UnauthorizedAccessException: Access to the path 'C:\Users\gowdyn\Documents\Visual Studio 2008\Projects\hybrid\hybrid\temp_loginimages\enviromental.jpg' is denied. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.File.Delete(String path) at hybrid.User_Controls.Imgloader_Add_Edit_Tbl.btnUpdate_Click(Object sender, EventArgs e) in C:\Users\gowdyn\Documents\Visual Studio 2008\Projects\hybrid\hybrid\User_Controls\Imgloader_Add_Edit_Tbl.ascx.cs:line 242
Any ideas?
According to File.Delete Method...
An UnauthorizedAccessException means one of 4 things:
The caller does not have the required permission.
The file is an executable file that is in use.
Path is a directory.
Path specified a read-only file.
I also had the problem, hence me stumbling on this post. I added the following line of code before and after a Copy / Delete.
Delete
File.SetAttributes(file, FileAttributes.Normal);
File.Delete(file);
Copy
File.Copy(file, dest, true);
File.SetAttributes(dest, FileAttributes.Normal);
This is an old issue, but I ran into it while searching. Turns out that I was missing the actual filename component in the save path for SaveAs...
string uploadPath = Server.MapPath("~/uploads");
file.SaveAs(uploadPath); // BAD
file.SaveAs(Path.Combine(uploadPath, file.FileName)); // GOOD
When a user tries to connect to your Web site, IIS assigns the connection to the IUSER_ComputerName account, where ComputerName is the name of the server on which IIS is running. By default, the IUSER_ComputerName account is a member of the Guests group. This group has security restrictions. Try to grand access to IUSER_ComputerName to that folder
Here is very good described answer about IIS security
Hope this helps
I got the error because I didn't realize that the destination should be a file. I had a folder as the second parameter (which works in cmd). and I got Unhandled Exception: System.UnauthorizedAccessException: Access to the path is denied. because C# File.Move wants a file there, not just for the first parameter, but for the second too, and so if you put a directory as second parameter, it's trying to write a file like c:\crp when you have a directory called c:\crp.
this would be incorrect File.Move(args[0],"c:\\crp");
So, this would be correct File.Move(args[0],"c:\\crp\\a.a");
The same goes for File.Copy
Right-click on Visual studio and click Run as Administrator
Thanks for +1
If this is an IIS website that is having the problem, check the Identity property of the advanced settings for the application pool that the site or application uses. You may find that it is set to ApplicationPoolIdentity, and in that case then this is the user that will have to have access to the path.
Or you can go old style and simply set the Identity to Network Service, and give the Network Service user access to the path.
You need to modify the privileges of the folder you're trying to delete from/save to. Right-click on the containing folder and use the Security tab to permit modify rights for the user your application runs under.
An UnauthorizedAccessException exception is thrown when the operating system denies access because of an I/O error or a security error.
If you are attempting to access a file or registry key, make sure it is not read-only.
I have also faced this issue when my window service started throwing the exception
System.UnauthorizedAccessException: Access to the path "C:\\Order\\Media
44aa4857-3bac-4a18-a307-820450361662.mp4" is denied.
So as a solution, I checked the user account associated with my service, as shown in below screen capture
So in my case it was NETWORK SERVICE
And then went to the folder properties to check if the associated user account also exists under their permission tab. It was missing in my case and when I added it and it fixed my issue.
For more information please check the below screen capture
same issue for me too,
I was pointing the folder instead of file.
so make sure in path, give path+filename
System.IO.File.WriteAllBytes("path", bytearray);
The exception that is thrown when the operating system denies access
because of an I/O error or a specific type of security error.
I hit the same thing. Check to ensure that the file is NOT HIDDEN.
Check your files properties. If the read-only is checked, uncheck it. This was my personal issue with the UnauthorizedAccessException.
I got this error and solved it in just a moment. Don't know why all of my folders are read-only，I cancelled the read-only and apply it. However, it is still read-only. So I moved the file into the root folder, it works - so weird.
I was facing this error because
Sometimes when I Combine the path with File Name and FileName = ""
It become Path Directory not a file which is a problem as mentioned above
so you must check for FileName like this
if(itemUri!="")
File.Delete(Path.Combine(RemoteDirectoryPath, itemUri));
I was trying to use System.IO.File.OpenWrite(path)
and it did not work because I was only passing OpenWrite() a path to a directory, but it requires a path all the way to the file you want to write. So a full path including the filename.extension at the end needs to be passed into OpenWrite to avoid UnauthorizedAccessException
In my case the problem was Norton. My in-house program doesn't have the proper digital signature and when it tried to delete a file it gave the UnauthorizedAccessException.
If it give you a notification, you can handle it from there. In my case it didn't give a notification that I noticed. So here's how to keep Norton from blocking the program.
Open Norton
Click the down arrow
Click History
Find activity by program
Click More Options
Click Exclude Process
To solve this problem, I follow the Scot Hanselman approach at Debugging System.UnauthorizedAccessException (often followed by: Access to the path is denied) article, the code with example is bellow:
class Program
{
static void Main(string[] args)
{
var path = "c:\\temp\\notfound.txt";
try
{
File.Delete(path);
}
catch (UnauthorizedAccessException)
{
FileAttributes attributes = File.GetAttributes(path);
if ((attributes & FileAttributes.ReadOnly) == FileAttributes.ReadOnly)
{
attributes &= ~FileAttributes.ReadOnly;
File.SetAttributes(path, attributes);
File.Delete(path);
}
else
{
throw;
}
}
}
}
I had the same problem on a newly moved website on a shared server. Solved through the web host panel (DotNetPanel) setting true the "allow write permissions". So if you are in a shared server before reviewing all code worth taking a look at the server configuration and could save you a lot of time.
Be aware that if you are trying to reach a shared folder path from your code, you dont only need to give the proper permissions to the physicial folder thru the security tab. You also need to "share" the folder with the corresponding app pool user thru the Share Tab
I had the exact error when deleting a file. It was a Windows Service running under a Service Account which was unable to delete a .pdf document from a Shared Folder even though it had Full Control of the folder.
What worked for me was navigating to the Security tab of the Shared Folder > Advanced > Share > Add.
I then added the service account to the administrators group, applied the changes and the service account was then able to perform all operations on all files within that folder.
For those trying to make a UWP (Universal Windows) application, file permissions are much more restricted, and in general is deny by default. It also supersedes the system user permissions. You will basically only have access to files in either
Your install location
Your AppData location
Files selected through the File or Folder picker
Locations requested in your App Manifest
You can read more here for details => https://learn.microsoft.com/en-us/windows/uwp/files/file-access-permissions
If you're using BitDefender there's a good chance its Safe Files feature blocked your operation. This is a form of Ransomware protection that comes with some of its more advanced versions.
Make sure to grant your application access in BitDefender and try again.
Some more details can be found in this BitDefender support page.
In my case it was my AVG anti-virus that triggered the exception.
I added my VS Projects directory to the "Allowed" list. And I had to add the executable to the AVG exceptions list after I copied the .exe to my App directory.
I've had the same problem and I've managed to get it working by changing the partition on which the file will be saved. So, on line 5 I've changed #"C:\" to be #"D:\" and that resolved the problem.
static void SaveVideoToDisk(string link)
{
var youTube = YouTube.Default; // starting point for YouTube actions
var video = youTube.GetVideo(link); // gets a Video object with info about the video
File.WriteAllBytes(#"D:\" + video.FullName, video.GetBytes());
}
After migrating from Visual Studio 2017 to Visual Studio 2019 I faced two exceptions with two of my applications which run properly under Visual Studio 2017:
System.UnauthorizedAccessException
System.ArgumentException
It turned out that I had to add the executables of the two applications to the allowed apps of Avast Antivirus.
I too faced the same problem when trying to do this after deployment at server:
dirPath = Server.MapPath(".") + "\\website\\" + strUserName;
if (!Directory.Exists(dirPath))
{
DirectoryInfo DI = Directory.CreateDirectory(dirPath);
}
string filePath = Server.MapPath(".") + "\\Website\\default.aspx";
File.Copy(filePath, dirPath + "\\default.aspx", true);
File.SetAttributes(dirPath + "\\default.aspx", FileAttributes.Normal);
I granted permission in IIS to other group including administrator and my problem got solved.
In my particular case I was repeatedly creating and deleting 10000 folders. It seems to me that the problem was in that although the method Directory.Delete(path, true) returns, the underling OS mechanism may still be deleting the files from the disk. And when I am starting to create new folders immediately after deletion of old ones, some of them are still locked because they are not completely deleted yet. And I am getting System.UnauthorizedAccessException: "Access to the path is denied".
Using Thread.Sleep(5000) after Directory.Delete(path, true) solves that problem. I absolutely agree that this is not safe, and I am not encouraging anyone to use it. I would love to here a better approach to solve this problem to improve my answer. Now I am just giving an idea why this exception may happen.
class Program
{
private static int numFolders = 10000;
private static string rootDirectory = "C:\\1";
static void Main(string[] args)
{
if (Directory.Exists(rootDirectory))
{
Directory.Delete(rootDirectory, true);
Thread.Sleep(5000);
}
Stopwatch sw = Stopwatch.StartNew();
CreateFolder();
long time = sw.ElapsedMilliseconds;
Console.WriteLine(time);
Console.ReadLine();
}
private static void CreateFolder()
{
var one = Directory.CreateDirectory(rootDirectory);
for (int i = 1; i <= numFolders; i++)
{
one.CreateSubdirectory(i.ToString());
}
}
}
First just check the path if the colon(:) character is missing or not after the drive letter. If colon is not missing then you can check if access/write permission is granted for that path.
I had the same issue and i was only missing the colon, permission and everything else was fine.
C:\folderpath
will work fine but,
C\folderpath .........(missing colon)
will give you access denial error.
I also ran into this post as dealing with the same issue. Looks like the file is in use and hence not able to write to it.
Though not able to figure it out, which process is using it. Signed out the other user who was logged in in that box, dont see any users who is holding it.
Any quick tips regarding on how to find the same.
Thanks,
Lakshay (developer)