I'm trying to write to the windows registry at HKEY_CURRENT_USER\Software\appname however I keep getting a permissions error when I attempt to write to the key, I have added the following to my assembly:
[assembly: RegistryPermissionAttribute(SecurityAction.RequestMinimum, Write = #"HKEY_CURRENT_USER\\Software")]
but this has not resolved the issue, is there something else that I should be doing?
I don't suppose it's something as simple as you having opened the key without specifying that you want write access? The OpenSubKey(string) method only gives read-only access.
The RegistryPermissionAttribute is part of the Code Access Security aka CAS, this is a permission system which checks the permission you have inside of the .NET framework, these permissions are defined by the security policy. There are 4 security policies:
Enterprise - policy for a family of machines that are part of an Active Directory installation.
Machine - policy for the current machine.
User - policy for the logged on user.
AppDomain - policy for the executing application domain.
The first 3 are configured in the configuration screen in the .NET Configuration tool, and the last is configured at runtime.
The reason why I explain this first is because the RegistryPermissionAttribute only checks your .NET permissions, it does not check the Operating System permissions.
You could use the System.Security.AccessControl to check the operating system permissions, but to get the permissions you'll probably need to either elevate or impersonate.
Make sure the app runs using the user-account that has enough rights to access the registry.
I don't see an answer or resolution here. I found this question when searching for something else.
The one thing I think that may be needed is that you need to be running as administrator if you're running from the exe. If you're running from VS you'll need to make sure that VS is running as administrator. VS will show "(Administrator) in the window title if it is.
This works for me. With key already there and without it. Without any special assembly attributes.
using System;
using Microsoft.Win32;
namespace WriteToRegistry {
class Program {
static void Main(string[] args) {
const string csRootKey = #"Software\MyCompany\Test";
using (RegistryKey loRegistryKey = Registry.CurrentUser.CreateSubKey(csRootKey)) {
if (loRegistryKey == null)
throw new InvalidOperationException("Could not create sub key " + csRootKey);
loRegistryKey.SetValue("CurrentTime", DateTime.Now.ToString(), RegistryValueKind.String);
}
}
}
}
EDIT: After rereading the question it seems that the problem could be OS permissions.
Related
Right now i am using an web application with code to read from and write to the registry. While debugging in Visual studio everything went fine but on the online test server it didn't run. the error exception message i am getting is:
System.Security.SecurityException: Requested registry access is not
allowed.
This is the code i am using:
private RegistryKey GetWritableBaseRegistryKey(string extendedPath)
{
var path = "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall";
return RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Default).OpenSubKey($"{path}\\{extendedPath}", true);
}
The sollutions i found where:
Solution 1
you will not be able to set AppPoolIdentity to a specific group, but
you can
create a local user (compmgmt.msc)
add the user to the administrator group (compmgmt.msc)
Set the application pool to run under that user, under Advanced Settings.
Obviously you know this is a very bad idea from a security
perspective, and should never ever ever be performed on a forward
facing server.
source
Solution 2
Create a separate console application to run the service in admin
modus so you could access the registry. This solution was performance
heavy because you need to run 2 separate applications.
Solution 3
Use this code to allow access to the registry.
RegistryPermission perm1 = new RegistryPermission(RegistryPermissionAccess.AllAccess, "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall");
perm1.Demand();
Or this code
RegistrySecurity rs = new RegistrySecurity();
string currentUserStr = Environment.UserDomainName + "\\" + Environment.UserName;
RegistryAccessRule accessRule = new RegistryAccessRule(currentUserStr, RegistryRights.WriteKey | RegistryRights.ReadKey | RegistryRights.Delete | RegistryRights.FullControl, AccessControlType.Allow);
rs.AddAccessRule(accessRule);
But these didn't work on the server however while debugging in visual studio the code ran fine.
In order for the web application to access the registry it must have sufficient permission. Consequently Solution 1 is the only one likely to work. It describes setting the web sites application pool to a user in the local administrators group. Its misses the steps about actually setting your IIS web site to use the newly created App Pool, which is why it might not work for you.
The technical process of reading a restricted registry, especially the application Uninstall registry key, inside a web server is really unlikely to be useful to you. Of what possible use is allowing a web server to access the servers own Application uninstall list going to be ?
I suspect you intend to open that registry key on the client's PC (my speculation) which is not going to be possible.
I am trying to add a registry key in my C# code under
HKEY_CLASSES_ROOT\*\shell\blabla
I want the user to be able to send any file to my application, kind of like Open with UltraEdit or so.
I don't have administrator rights and the users won't have administrator privileges, too.
If I am doing that in my C# code as posted below, I get a
System.UnauthorizedAccessException
Registry.SetValue("HKEY_CLASSES_ROOT\\*\\shell\\blabla", null, "FastSearch");
string path = Application.ExecutablePath;
Registry.SetValue("HKEY_CLASSES_ROOT\\*\\shell\\blabla" + "\\Command", null, path + " \"%1\"");
If I run Regedit and attempt to do it manually myself, I get a similar error:
Error! Key could not be created. Error when writing to the registry.
BUT, if I double click a *.reg file that attempts to write the SAME KEY, everything works!
So why is that?
And do I have a chance to get this done through code?
Or should I just change my code to run that *.reg file?
UPDATE:
Actually the *.reg file did not write the SAME KEY as stated above, but
HKEY_CURRENT_USER\Software\Classes\*\shell\blabla
I didn't notice that. It seems as anything added under HKEY_CURRENT_USER\Software\Classes*\shell\blabla is also added to HKEY_CLASSES_ROOT\*\shell\blabla. Sorry for the confusion.
Although the problem is solved already and the reason for successful import of *.reg file was found out also in the meantime in comparison to C# code, here is a complete answer for this question.
HKEY_CLASSES_ROOT Key (short HKCR) as described by Microsoft shows file name extension associations and COM class registration information which are effective for the current user.
The real locations in registry for those keys are:
HKEY_LOCAL_MACHINE\Software\Classes (short HKLM\Software\Classes) containing the defaults for all users using a machine and
HKEY_CURRENT_USER\Software\Classes (short HKCU\Software\Classes) containing the user specific settings which override the default settings from HKLM\Software\Classes.
A registry write to HKEY_CLASSES_ROOT is always redirected to HKLM\Software\Classes. A write access to any key in HKLM requires administrative privileges which is the reason for the error message.
Microsoft recommends to write directly to either HKLM\Software\Classes or to HKCU\Software\Classes depending on changing the defaults or the effective file associations for the current user.
Write operations to keys under HKCU do not require administrative privileges.
HKCR should be used only for reading currently effective settings for file name extension associations and COM class registration information and not for adding or changing them.
I am trying to check if I have write access to a specific key in the registry before displaying a form that allow the user to change some settings that are written in that key.
code sanitized for clarity
public bool CanWrite()
{
string key = #"HKEY_LOCAL_MACHINE\SOFTWARE\MyHaccpPlan, Inc.\2.0";
try
{
RegistryPermission permission = new RegistryPermission(RegistryPermissionAccess.Write, key);
permission.Demand();
return true;
}
catch(SecurityException)
{
return false;
}
}
I am running the application using a user that has read access only. The problem is that this function return true, even if the user don't have write access.
Later, a call like
Registry.SetValue(#"HKEY_LOCAL_MACHINE\SOFTWARE\MyHaccpPlan, Inc.\2.0", "Language", "fr-CA");
will fail with UnauthorizedAccessException.
How do I properly check for registry rights before attempting to write to it?
Edit
I don't want the current user to be able to write there. I want to use this registry entry as a flag that a feature in the software should be disabled. But if the user is an administrator, I want the software to allow the feature. The goal is that a network administrator could be able to preset the settings and that the users will be unable to change them.
But beside actually writing and waiting for it to crash, I want to check the security using the permission system offered in .NET if that is possible.
You shouldn't rely on .NET code access security for managing access control to the registry; let alone should you have explicit checks in your code. With that approach, the user can still use the registry editor and bypass all your access checks.
Instead, you should use proper ACLs to restrict what users can write to a key.
If you want to test at run-time whether you have access to a key, you should try to open the key for writing, and catch SecurityException (in which case the user running the application has no permission to modify the key).
mmm you can try using a tool like Lutz Roeder's Reflector for viewing the content of the Registry.SetValue Method.
Looking a bit to it, it seems to do it with next line of code:
new SecurityPermission(SecurityPermissionFlag.UnmanagedCode).Demand();
I have the following C# code
using (RunspaceInvoke invoker = new RunspaceInvoke())
{
invoker.Invoke("Set-ExecutionPolicy Unrestricted");
// ...
}
which gives me the exception
Access to the registry key
'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PowerShell\1\ShellIds\Microsoft.PowerShell'
is denied.
According to this, the solution is to start PowerShell as an administrator.
Ordinarily, this can be accomplished by right-clicking PowerShell and selecting "Run as Administrator". Is there a way to do this programmatically?
I know this is an old post, but we ran into this same problem recently.
We had to scope the execution policy on the machine running the C# code by running the following from PowerShell...
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy Unrestricted
When we had done this previously, without scoping, we were setting the execution policy for Administrator. Visual Studio \ C# was running as the current user, causing it to fail with insufficient permissions.
Check this out
You need to impersonate as an administrator to do it (you will of course need administrator credentials)
Check that article, that also comes with code ready to use (I've used it and it works great)
Basically, you need to do this:
using ( new Impersonator( "myUsername", "myDomainname", "myPassword" ) )
{
using (RunspaceInvoke invoker = new RunspaceInvoke())
{
invoker.Invoke("Set-ExecutionPolicy Unrestricted");
}
}
Administrative privileges are at the application level. The app that needs admin access in this case is yours. Creating runspaces in C# in a custom app does not invoke powershell the application - it just loads some assemblies into your application.
That said, you can elevate as the other poster said although embedding admin usernames and passwords into source code make me feel ill.
-Oisin
I think an alternative model would be to wrap the powershell executor into a simple asp.net webapi webservice.
The webservice could then be configured to run with the required permissions needed to do it's job. It can provide it's own security to determine which clients can call it.
To execute a script, you would just call webservice methods. You could make the method quite general - script name and params.
It's a bit more work, but a lot more secure (see x0n's thoughts).
Strictly for DEV environment
This is relatively very old post.
But I have found a new way to do this.
I am hosting the C# web api on IIS 8 having some powershell code that I want to run with administrator privileges.
So I provided the admin credentials in the Application pool identity setting.
Just set administrator account in app pool identity.
Hope this helps to anyone. :)
This snippet works well if I try to write in a user directory but as soon as I try to write in Program Files, it just executes silently and the file has not been copied (no exception). If I try to copy the file in C:\ or in C:\Windows I catch an UnauthorizedAccessException.
Do you know another way to get the permissions to write in that directory or to make it work another way?
Any help greatly appreciated! Thanks
using(FileStream fs=File.Open(source, FileMode.Open)){ }
try
{
FileIOPermission fp = new FileIOPermission(FileIOPermissionAccess.Write,
AccessControlActions.Change, "C:\\Program Files\\MyPath");
fp.Demand(); //<-- no exception but file is not copied
File.Copy("C:\\Users\\teebot\\Documents\\File.xml","C:\\Program Files\\MyPath\\File.xml",true);
}
catch(SecurityExceptions)
{
throw(s);
}
catch(UnauthorizedAccessException unauthroizedException)
{
throw unauthroizedException;
}
If you are running under Vista then the system just redirects writes to the program files folder, this is done so old program that keep their configuration in the program directory will continue to work when the user is not an Admin (or UAC is enabled).
All you have to do is add a manifest to your program that specify the required access level, then the system assume your program is Vista-aware and turns off all those compatibility patches.
You can see an example of a manifest file on my blog at:
http://www.nbdtech.com/blog/archive/2008/06/16/The-Application-Manifest-Needed-for-XP-and-Vista-Style-File.aspx
(the focus of the post is on getting the right version of the common controls, but the Vista security declarations are also there)
Don't write in the Program Files folder.
That's a big no-no, and will especially cause problems when the day comes where your code runs in Vista or on a machine at a company where users only get standard security rather than admin rights. Use the Application Data folder instead.
Are you running on Vista? If so then you may be running into file system virtualization. This is a feature in 32 bit versions of Vista which allows a normal user to write to protected parts of the file system. It's a shim introduced to reduce the pain of the LUA features of Vista.
The short version is that the operating system will create a virtual file system for certain protected roots (such as program files). When a non-admin attempts to write to it, a copy will be created an editted instead of the original. When your user account attempts to look at the file it will see the edit.s Other user accounts will only see the original.
Longer Version: http://thelazyadmin.com/blogs/thelazyadmin/archive/2007/04/26/file-system-virtualization.aspx
Code access security grants or denies permissions to your code.
It can't be used to override permissions that are granted/denied to the current user.