Initial attempts to add a check method

modules/exploits/windows/local/cve_2020_0787_bits_arbitrary_file_move.rb

@@ -77,6 +77,33 @@ class MetasploitModule < Msf::Exploit::Local
     ])
   end
 
+  def check
+    sysinfo_value = sysinfo['OS']
+
+    if sysinfo_value !~ /windows/i
+      # Non-Windows systems are definitely not affected.
+      return Exploit::CheckCode::Safe
+    end
+
+    build_num_raw = cmd_exec("cmd.exe /c ver")
+    build_num = build_num_raw.match(/\d+\.\d+\.\d+\.\d+/)[0]
+    print_status("Windows System Version: #{build_num_raw}")
+    print_status("Build number: #{build_num}")
+    # see https://docs.microsoft.com/en-us/windows/release-information/
+    unless build_num =~ /(7|8|8\.1|10|2008|2012|2016|2019|1803|1903)/
+      print_error("Target is not running a vulnerable version of Windows!")
+      return CheckCode::Safe
+    end
+
+    #disable_compression = registry_getvaldata('HKLM\\SYSTEM\\CurrentControlSet\\Services\\LanmanServer\\Parameters', 'DisableCompression')
+    #if !disable_compression.nil? && disable_compression != 0
+    #  print_error('The exploit requires compression to be enabled')
+    #  return CheckCode::Safe
+    #end
+
+    CheckCode::Appears
+  end
+
   def check_target_is_running_windows_10
     if sysinfo['OS'].match('Windows').nil?
       fail_with(Failure::NotVulnerable, 'Target is not running Windows!')