fix for smb_login errors

do not try the TreeConnect if the SESSION_SETUP
has already failed.

Author: David Maloney

Gemfile.lock

@@ -343,7 +343,7 @@ GEM
       rspec-mocks (~> 3.6.0)
       rspec-support (~> 3.6.0)
     rspec-support (3.6.0)
-    ruby_smb (0.0.12)
+    ruby_smb (0.0.14)
       bindata
       rubyntlm
       windows_error

lib/metasploit/framework/login_scanner/smb.rb

@@ -100,19 +100,21 @@ def attempt_login(credential)
             client      = RubySMB::Client.new(self.dispatcher, username: username, password: password, domain: realm)
             status_code = client.login
 
-            # Windows SMB will return an error code during Session
-            # Setup, but nix Samba requires a Tree Connect. Try admin$
-            # first, since that will tell us if this user has local
-            # admin access. Fall back to IPC$ which should be accessible
-            # to any user with valid creds.
-            begin
-              tree = client.tree_connect("\\\\#{host}\\admin$")
-              # Check to make sure we can write a file to this dir
-              if tree.permissions.add_file == 1
-                access_level = AccessLevels::ADMINISTRATOR
+            if status_code == WindowsError::NTStatus::STATUS_SUCCESS
+              # Windows SMB will return an error code during Session
+              # Setup, but nix Samba requires a Tree Connect. Try admin$
+              # first, since that will tell us if this user has local
+              # admin access. Fall back to IPC$ which should be accessible
+              # to any user with valid creds.
+              begin
+                tree = client.tree_connect("\\\\#{host}\\admin$")
+                # Check to make sure we can write a file to this dir
+                if tree.permissions.add_file == 1
+                  access_level = AccessLevels::ADMINISTRATOR
+                end
+              rescue Exception => e
+                client.tree_connect("\\\\#{host}\\IPC$")
               end
-            rescue Exception => e
-              client.tree_connect("\\\\#{host}\\IPC$")
             end
 
             case status_code.name