AuthorizeAD filter

Authorize.cs

/// This allows you to use an authorization filter on controller actions tied to an AD Security Group, such as [AuthorizeAD(Groups = "MIS")]

public class AuthorizeADAttribute : AuthorizeAttribute {
    public string Groups { get; set; }

    protected override bool AuthorizeCore(HttpContextBase httpContext) {
      if (base.AuthorizeCore(httpContext)) {
        if (String.IsNullOrEmpty(Groups))
          return true;

        string adPath = WebConfigurationManager.ConnectionStrings["ADPath"].ToString(); //pull the AD connection string from Web.config

        DirectoryEntry directoryEntry = new DirectoryEntry();
        DirectoryEntry root = new DirectoryEntry(adPath);
        DirectorySearcher searcher = new DirectorySearcher();
        searcher.SearchRoot = root;
        searcher.SearchScope = SearchScope.Subtree;
        searcher.Filter = "(SAMAccountName=" + httpContext.User.Identity.Name + ")";
        searcher.CacheResults = false;
        SearchResult result = searcher.FindOne();

        // Get the AD groups specified in the [AuthorizeAD] attribute
        // [AuthorizeAD(Groups = "MIS, Retail")]
        var groups = Groups.Split(',').ToList<string>();

        // Check to see if user is in the given Security Group
        foreach (string group in groups) {
          foreach (string member in result.Properties["memberOf"]) {
            Match match = Regex.Match(member, @"CN=" + group.Trim());
            if (match.Success) {
              return true;
            }
          }
        }
      }
      return false;
    }
  }