I want to set "Password Must Change at Next Login" flag

Question

In my application, I am doing things that a user can control his/her local Windows User account from my app i.e. creating user, set/remove password, change password and also invoking password expiration policy is possible from my app. Now, at this point, I need to figure out If user wants to change his password at next login, then what happens. As many forums and blogs say about this, I did coding accordingly:

Invoke Password Expire at Next Login

 public bool InvokePasswordExpiredPolicy()
    {
        try
        {
            string path = GetDirectoryPath();
            string attribute = "PasswordExpired";
            DirectoryEntry de = new DirectoryEntry(path);
            de.RefreshCache(new string[] { attribute });
            if(de.Properties.Contains("PasswordExpired"))
            de.Properties[attribute].Value = 1;
            de.CommitChanges();
            return true;
        }
        catch (Exception)
        {
            return false;
        }
    }

Provoke Password Expire at Next Login. Reset the flag

public bool ProvokePasswordExpiredPolicy()
    {
        try
        {
            string path = GetDirectoryPath();
            string attribute = "PasswordExpired";
            DirectoryEntry de = new DirectoryEntry(path);
            de.RefreshCache(new string[] { attribute });
            de.Properties[attribute].Value = -1;
            de.CommitChanges();
            return true;
        }
        catch (Exception)
        {
            return false;
        }
    }

Checking for whether concerned flag is set or not

public bool isPasswordPolicyInvoked()
    {
        try
        {
            string path = GetDirectoryPath();
            string attribute = "PasswordExpired";
            DirectoryEntry de = new DirectoryEntry(path);
            de.RefreshCache(new string[] { attribute });
            int value = Convert.ToInt32(de.Properties[attribute].Value);

            if (value == 1)
                return true;
            else
                return false;
        }
        catch (Exception)
        {
            return false;
        }
    }

I am using WinNT to get the directory path rather than LDAP. I used the following method to get the directory path.

private String GetDirectoryPath()
    {
        String uName = this.userName;
        String mName = this.userMachine;

        String directoryPath = "WinNT://" + mName + "/" + uName;

        return directoryPath;
    }

is there anything I am missing? Help me out here.

Note: Firstly, I used pwdLastSet attribute to be set to 0(for on) and -1(for off) that throws an exception "Directory Property Not found in Property Cache", later I discovered that WinNT doesn't support this attribute rather it supports PasswordExpired which needs to be 1 to set the flag. That's what I did.

Answer 1

How about using System.DirectoryServices.AccountManagement instead, in which case you can call the following code:

UserPrincipal.Current.ExpirePasswordNow();

Answer 2

The code below should work:

de.Properties["pwdLastSet"][0] = 0;

From User Must Change Password at Next Logon (LDAP Provider):

To force a user to change their password at next logon, set the pwdLastSet attribute to zero (0). To remove this requirement, set the pwdLastSet attribute to -1. The pwdLastSet attribute cannot be set to any other value except by the system.