How to apply Windows group policy using .NET?

Question

Is it possible to apply (and remove) Windows group policy settings using .NET?

I am working on an application that needs to temporarily put a machine into a restricted, kiosk-like state. One of the things I need to control is access to USB drives which I believe I can do through group policy. I'd like my app to set the policy when it starts and revert the change when it exits... is this something I can do through .NET framework calls?

These are my primary requirements:

• Apply group policy settings when my console app is started.
• Identify when a user action is denied by the policy and log it.
  • Logging to the system security log is acceptable.
• Revert my policy changes when my app stops.

Airboat

Seems to me that running your app as a limited user is much more secure than running as an elevated user that can change group policies on the computer. – Signboard

Agreed, but that doesn't work for this particular scenario. This app gets installed on systems I don't control just long enough for a user to perform some timed actions within the restricted sandbox we provide, and then my app is removed. I can't assume that a sufficiently restricted user account already exists, hence my desire to create the environment on the fly. – Airboat

I don't think you can change the local policy through managed code. This can only be done through the IGroupPolicyObject in C\C++ – Khadijahkhai

Answer 1

Try using IGroupPolicyObject

bool SetGroupPolicy(HKEY hKey, LPCTSTR subKey, LPCTSTR valueName, DWORD dwType, const BYTE* szkeyValue, DWORD dwkeyValue)
{
    CoInitialize(NULL);
    HKEY ghKey, ghSubKey, hSubKey;
    LPDWORD flag = NULL;
    IGroupPolicyObject *pGPO = NULL;
    HRESULT hr = CoCreateInstance(CLSID_GroupPolicyObject, NULL, CLSCTX_ALL, IID_IGroupPolicyObject, (LPVOID*)&pGPO);

    if(!SUCCEEDED(hr))
    {
        MessageBox(NULL, L"Failed to initialize GPO", L"", S_OK);
    }

    if (RegCreateKeyEx(hKey, subKey, 0, NULL, REG_OPTION_NON_VOLATILE, KEY_WRITE, NULL, &hSubKey, flag) != ERROR_SUCCESS)
    {
        return false;
        CoUninitialize();
    }

    if(dwType == REG_SZ)
    {
        if(RegSetValueEx(hSubKey, valueName, 0, dwType, szkeyValue, strlen((char*)szkeyValue) + 1) != ERROR_SUCCESS)
        {
            RegCloseKey(hSubKey);
            CoUninitialize();
            return false;
        }
    }

    else if(dwType == REG_DWORD)
    {
        if(RegSetValueEx(hSubKey, valueName, 0, dwType, (BYTE*)&dwkeyValue, sizeof(dwkeyValue)) != ERROR_SUCCESS)
        {
            RegCloseKey(hSubKey);
            CoUninitialize();
            return false;
        }
    }

    if(!SUCCEEDED(hr))
    {
        MessageBox(NULL, L"Failed to initialize GPO", L"", S_OK);
        CoUninitialize();
        return false;
    }

    if(pGPO->OpenLocalMachineGPO(GPO_OPEN_LOAD_REGISTRY) != S_OK)
    {
        MessageBox(NULL, L"Failed to get the GPO mapping", L"", S_OK);
        CoUninitialize();
        return false;
    }

    if(pGPO->GetRegistryKey(GPO_SECTION_USER,&ghKey) != S_OK)
    {
        MessageBox(NULL, L"Failed to get the root key", L"", S_OK);
        CoUninitialize();
        return false;
    }

    if(RegCreateKeyEx(ghKey, subKey, 0, NULL, REG_OPTION_NON_VOLATILE, KEY_WRITE, NULL, &ghSubKey, flag) != ERROR_SUCCESS)
    {
        RegCloseKey(ghKey);
        MessageBox(NULL, L"Cannot create key", L"", S_OK);
        CoUninitialize();
        return false;
    }

    if(dwType == REG_SZ)
    {
        if(RegSetValueEx(ghSubKey, valueName, 0, dwType, szkeyValue, strlen((char*)szkeyValue) + 1) != ERROR_SUCCESS)
        {
            RegCloseKey(ghKey);
            RegCloseKey(ghSubKey);
            MessageBox(NULL, L"Cannot create sub key", L"", S_OK);
            CoUninitialize();
            return false;
        }
    }

    else if(dwType == REG_DWORD)
    {
        if(RegSetValueEx(ghSubKey, valueName, 0, dwType, (BYTE*)&dwkeyValue, sizeof(dwkeyValue)) != ERROR_SUCCESS)
        {
            RegCloseKey(ghKey);
            RegCloseKey(ghSubKey);
            MessageBox(NULL, L"Cannot set value", L"", S_OK);
            CoUninitialize();
            return false;
        }
    }

    if(pGPO->Save(false, true, const_cast<GUID*>(&EXTENSION_GUID), const_cast<GUID*>(&CLSID_GPESnapIn)) != S_OK)
    {
        RegCloseKey(ghKey);
        RegCloseKey(ghSubKey);
        MessageBox(NULL, L"Save failed", L"", S_OK);
        CoUninitialize();
        return false;
    }

    pGPO->Release();
    RegCloseKey(ghKey);
    RegCloseKey(ghSubKey);
    CoUninitialize();
    return true;
}

You can call this function like this..

// Remove the Log Off in start menu
SetGroupPolicy(HKEY_CURRENT_USER,
    L"Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer",
    L"StartMenuLogOff", REG_DWORD, NULL, 1);

Tumpline

Thanks for the answer. Unfortunately I was looking for something in C#, although I probably should have specified that. Even though this doesn't help me I'm flagging it as the correct answer because its the best answer to the question that I actually asked and most likely to help someone searching for a similar solution. – Airboat

What would be the values HKEY_CURRENT_USER?? and REG_DWORD???for example? – Cheshvan

@SethPetry-Johnson What would be the values HKEY_CURRENT_USER?? and REG_DWORD???for example? – Cheshvan

This post is missing critical info. What are the headers? What are the libs needed? #include <GPEdit.h> is needed but I can't find why I'm getting linking errors when using CLSID_GPESnapIn – Caenogenesis

Answer 2

NOTE: I use two GroupPolicy assembly references: C:\Windows\assembly\GAC_MSIL\Microsoft.GroupPolicy.Management\2.0.0.0__31bf3856ad364e35\Microsoft.GroupPolicy.Management.dll and C:\Windows\assembly\GAC_32\Microsoft.GroupPolicy.Management.Interop\2.0.0.0__31bf3856ad364e35\Microsoft.GroupPolicy.Management.Interop.dll This framework 2.0, so there are mixed code, and you must use app.config: http://msmvps.com/blogs/rfennell/archive/2010/03/27/mixed-mode-assembly-is-built-against-version-v2-0-50727-error-using-net-4-development-web-server.aspx

I made it like that.

using System.Collections.ObjectModel;
using Microsoft.GroupPolicy;
using Microsoft.Win32;

/// <summary>
/// Change user's registry policy
/// </summary>
/// <param name="gpoName">The name of Group Policy Object(DisplayName)</param>
/// <param name="keyPath">Is KeyPath(like string path=@"Software\Microsoft\Windows\CurrentVersion\Policies\Explorer")</param>
/// <param name="typeOfKey">DWord, ExpandString,... e.t.c </param>
/// <param name="parameterName">Name of parameter</param>
/// <param name="value">Value</param>
/// <returns>result: true\false</returns>
public bool ChangePolicyUser(string gpoName, string keyPath, RegistryValueKind typeOfKey, string parameterName, object value)
    {
        try
        {
            RegistrySetting newSetting = new PolicyRegistrySetting();
            newSetting.Hive = RegistryHive.CurrentUser;
            newSetting.KeyPath = keyPath;
            bool contains = false;
            //newSetting.SetValue(parameterName, value, typeOfKey);
            switch (typeOfKey)
            {
                case RegistryValueKind.String:
                    newSetting.SetValue(parameterName, (string)value, typeOfKey);
                    break;
                case RegistryValueKind.ExpandString:
                    newSetting.SetValue(parameterName, (string)value, typeOfKey);
                    break;
                case RegistryValueKind.DWord:
                    newSetting.SetValue(parameterName, (Int32)value);
                    break;
                case RegistryValueKind.QWord:
                    newSetting.SetValue(parameterName, (Int64)value);
                    break;
                case RegistryValueKind.Binary:
                    newSetting.SetValue(parameterName, (byte[])value);
                    break;
                case RegistryValueKind.MultiString:
                    newSetting.SetValue(parameterName, (string[])value, typeOfKey);
                    break;
            }
            Gpo gpoTarget = _gpDomain.GetGpo(gpoName);
            RegistryPolicy registry = gpoTarget.User.Policy.GetRegistry(false);
            try
            {
                ReadOnlyCollection<RegistryItem> items = gpoTarget.User.Policy.GetRegistry(false).Read(newSetting.Hive, keyPath);
                foreach (RegistryItem item in items)
                {
                    if (((RegistrySetting) item).ValueName == parameterName)
                    {
                        contains = true;
                    }
                }
                registry.Write((PolicyRegistrySetting) newSetting, !contains);
                registry.Save(false);
                return true;
            }
            catch (ArgumentException)
            {
                registry.Write((PolicyRegistrySetting)newSetting, contains);
                registry.Save(true);
                return true;
            }
        }
        catch (Exception)
        {
            return false;
        }
    }

Matronize