What is Cross-Site Contamination and How to Prevent it
If you suffer multiple reinfections and your site is one of many in an account, the odds are high that you’re suffering from cross-site contamination.
Cross-site contamination is when a site is negatively affected by neighboring sites within the same account/server due to poor isolation on the server and/or account configuration. This phenomenon is one of the greatest contributors to the VPS/Dedicated/Shared hosting secure or insecure debate.
The greatest contributor to cross-site contamination is what I call soup-kitchen servers.