I am trying to install Prestashop and spoke with the technical support representative from BlueHost regarding questions I had on setting the file permissions to 777 as stated in the following installation instructions:
Each '7' in 777 means 'read'+'write'+'execute'. First digit defines permissions for file ouwner, second digit is for group and last digit for everyone 'other'.
Let's assume the file belongs to 'root' (aka system administrator'). Last '7' permits anyone to modify this file. So any unprivileged user may write into it some program which when executed by 'root' will give administrative privileges to anyone.
It is definitely dangerous.