Resolve rapid7#4408 - bad uncaught nil get_once

Author: wchen-r7

modules/auxiliary/scanner/misc/ib_service_mgr_info.rb

@@ -154,7 +154,7 @@ def run_host(ip)
 
       sock.put(buf)
 
-      response = sock.get_once
+      response = sock.get_once || ''
 
       # print(Rex::Text.to_hex_dump(response))
 
@@ -198,7 +198,7 @@ def run_host(ip)
 
       sock.put(buf)
 
-      response = sock.get_once
+      response = sock.get_once || ''
 
       res = response.unpack('x28Z*Z*')
 

modules/auxiliary/scanner/misc/poisonivy_control_scanner.rb

@@ -66,9 +66,9 @@ def run_host(ip)
             )
             r << [ip,port,"open",'Unknown']
             s.puts("\x00"*0x100,0) #Send 0x100 zeros, wait for answer
-            data = s.get_once(0x100)
+            data = s.get_once(0x100) || ''
             if data.length == 0x100
-              data = s.get_once(0x4)
+              data = s.get_once(0x4) || ''
               if data == "\xD0\x15\x00\x00" #Signature for PIVY C&C
                 print_status("#{ip}:#{port} - C&C Server Found")
                 r << [ip,port,"open",'Poison Ivy C&C']

modules/auxiliary/scanner/misc/zenworks_preboot_fileaccess.rb

@@ -63,8 +63,20 @@ def run_host(ip)
     sock.put(packet)
     sock.get_once(4, 1)
     length = sock.get_once(4, 1)
+
+    unless length
+      print_error("Unable to get length due to a timeout")
+      return
+    end
+
     sock.get_once(0x210-8, 1)
     contents = sock.get_once(length.unpack("V").first, 1)
+
+    unless contents
+      print_error("Unable to extract contents due to a timeout")
+      return
+    end
+
     disconnect
 
     print_status "File retrieved successfully!"

modules/auxiliary/scanner/rservices/rlogin_login.rb

@@ -218,7 +218,7 @@ def do_login(user, pass, luser, status = nil)
     sock.put("\x00#{luser}\x00#{user}\x00#{datastore['TERM']}/#{datastore['SPEED']}\x00")
 
     # Read the expected nul byte response.
-    buf = sock.get_once(1)
+    buf = sock.get_once(1) || ''
     return :abort if buf != "\x00"
 
     # NOTE: We report this here, since we are awfully convinced now that this is really

modules/auxiliary/scanner/scada/sielco_winlog_fileaccess.rb

@@ -65,7 +65,7 @@ def run_host(ip)
     packet << travs # Path traversal
     packet << "\x00"
     sock.put(packet)
-    response = sock.get_once(5, 1)
+    response = sock.get_once(5, 1) || ''
 
     if response.unpack("C").first != 0x78
       print_error "#{ip}:#{rport} - Error opening file"
@@ -84,7 +84,7 @@ def run_host(ip)
     packet << stream # stream
     packet << "\x00" * 7
     sock.put(packet)
-    response = sock.get_once(5, 1)
+    response = sock.get_once(5, 1) || ''
 
     if response.unpack("C").first != 0x79
       print_error "#{ip}:#{rport} - Error getting the file length"
@@ -106,7 +106,7 @@ def run_host(ip)
       response = ""
 
       while response.length < 0x7ac # Packets of 0x7ac (header (0x9) + block of data (0x7a3))
-        response << sock.get_once(0x7ac-response.length, 5)
+        response << sock.get_once(0x7ac-response.length, 5) || ''
       end
       if response.unpack("C").first != 0x98
         print_error "#{ip}:#{rport} - Error reading the file, anyway we're going to try to finish"
@@ -126,7 +126,7 @@ def run_host(ip)
     packet << "\x7B"
     packet << "\x00" * 11
     sock.put(packet)
-    response = sock.get_once(-1, 1)
+    response = sock.get_once(-1, 1) || ''
     if response.unpack("C").first != 0x7B
       print_error "#{ip}:#{rport} - Error closing file file, anyway we're going to try to finish"
     end

modules/auxiliary/scanner/ssh/detect_kippo.rb

@@ -29,9 +29,9 @@ def initialize(info = {})
 
   def run_host(ip)
     connect
-    banner = sock.get_once
+    banner = sock.get_once || ''
     sock.put(banner + "\n" * 8)
-    response = sock.get_once
+    response = sock.get_once || ''
 
     if response =~ /(?:^Protocol mismatch\.\n$|bad packet length)/
       print_good("#{ip}:#{rport} - Kippo detected!")

modules/auxiliary/scanner/vmware/vmauthd_version.rb

@@ -84,7 +84,7 @@ def run_host(ip)
 
   def do_login(user, pass, nsock=self.sock)
     nsock.put("USER #{user}\r\n")
-    res = nsock.get_once
+    res = nsock.get_once || ''
     unless res.start_with? "331"
       ret_msg = "Unexpected reply to the USER command: #{res}"
       return ret_msg

modules/auxiliary/scanner/x11/open_x11.rb

@@ -45,8 +45,11 @@ def run_host(ip)
 
       disconnect
 
-      if(response)
+      if response
         success = response[0,1].unpack('C')[0]
+      else
+        print_error("No response received due to a timeout")
+        return
       end