Hi,

I wanted a reliable way of detecting if a given NTAccount object
represents a user account or group account. I was using
SecurityIdentifier.IsAccountSid() method but this doesn't work as I
expected. It returns true for user accounts and also for groups created
by administrator. Right now I am using the WMI class
System.Management.ManagementClass to get a list of all local user
accounts and am iterating over them to see if the given account is a
user account.

        System.Management.ManagementClass mc = new
System.Management.ManagementClass("Win32_UserAccount");

System.Management.ManagementObjectCollection objColl =
mc.GetInstances();
foreach (System.Management.ManagementObject obj in objColl)
{
   String name = obj.GetPropertyValue("Name") as String;
   // Compare name and NTAccount.Value to detect if its a user
}

While this works, it seems unclean and a overtly complex way of doing
things. Does any one know of a clean straight forward way of doing
this?

Thanks,
Roshan

Hello,

you can use the LookupAccountSid or LookupAccountName function. These will
translate accountnames to sids and vice versa.

And you get the accountType:


        [DllImport("advapi32.dll", SetLastError = true, CharSet =
CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool LookupAccountSid(
            [In] string systemName,
            [In, MarshalAs(UnmanagedType.LPArray)] byte[] sid,
            [Out] StringBuilder name,
            [In, Out] ref uint nameLength,
            [Out] StringBuilder referencedDomainName,
            [In, Out] ref uint referencedDomainNameLength,
            [Out] out AccountType usage);


public enum AccountType
    {
        /// <summary>
        /// No account type
        /// </summary>
        None = 0,
        /// <summary>
        /// The account is a user
        /// </summary>
        User,
        /// <summary>
        /// The account is a security group
        /// </summary>
        Group,
        /// <summary>
        /// The account defines a domain
        /// </summary>
        Domain,
        /// <summary>
        /// The account is an alias
        /// </summary>
        Alias,
        /// <summary>
        /// The account is a well-known group, such as
BUILTIN\Administrators
        /// </summary>
        WellknownGroup,
        /// <summary>
        /// The account was deleted
        /// </summary>
        DeletedAccount,
        /// <summary>
        /// The account is invalid
        /// </summary>
        Invalid,
        /// <summary>
        /// The type of the account is unknown
        /// </summary>
        Unknown,
        /// <summary>
        /// The account is a computer account
        /// </summary>
        Computer
    }

Best regards,
Henning Krause

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