[.Net][ADSI]Get User Information from AD by SID

System.DirectoryService namespace provides many useful utilitu to communicate with AD, especially when you are querying object information. However, when querying AD object by objectSID, there’s a trick.

To query AD via System.DirectoryService namespace, first we have to create searcher object.

private static DirectorySearcher GetSearcher()

{

    DirectoryEntry de = new DirectoryEntry("LDAP://dc=mydomain,dc=com");

    DirectorySearcher ds = new DirectorySearcher(de);

    return ds;

}

Then to set query filter, in this case , I am searching objects by its sid.

ds.Filter = string.Format("(&(objectClass=user)(objectSid={0}))", ConvertByteToStringSid(binaryForm));

And to get correct SID string for query.

private static string ConvertByteToStringSid(Byte[] sidBytes)

{

    StringBuilder strSid = new StringBuilder();

    foreach (byte b in sidBytes)

    {

        strSid.Append("\\").Append(b.ToString("X2"));

    }

    return strSid.ToString();

}

We can not simply put filter like objectSid=S-1-5, to get this query work, we have to convert SID into format like \00\01\05…