Fix AES key length in cachedump module, fix rapid7#8525

Author: Rogdham

modules/post/windows/gather/cachedump.rb

@@ -253,7 +253,7 @@ def decrypt_hash(edata, nlkm, ch)
 
   def decrypt_hash_vista(edata, nlkm, ch)
     aes = OpenSSL::Cipher.new('aes-128-cbc')
-    aes.key = nlkm[16...-1]
+    aes.key = nlkm[16...32]
     aes.padding = 0
     aes.decrypt
     aes.iv = ch