How To Know That The Site Has Been Hacked

• In most of the case hacker upload their deface page.
• The search engine says that you run an attack site.
• Look either the email has been sent from your account.
• Anti-virus and antimalware said that your web used for phishing.

Ways That An Account Get Infected

• You are running an insecure and old script on your website and softwares are not patched well.
• Your computer has been hacked by any means and the attacker steal your website information from your own computer.

• Shutdown your website
• In the Webmaster Tools, use the URL removal tool to remove any hacked pages.
• If you have any kind of access into your website than change the passwords including email,ftp and cpanel etc.
• Change the old script and try to find out your other weakness.
• Be keeping your files up to date and update all the softwares running on the website patched it to prevent future attack.