If the server is attacked late, please show me my files and related questions.

If the server is attacked in the evening, please show me my file. what is the problem? my server is hacked this evening, as shown on the screen, followed by my modified homepage file, let's see how he came in. what is my vulnerability? Index. php & lt; title & gt; # Hacked & nbsp; By & nbsp; Ramzi & nbsp the server is attacked at night. Please check out my files. what is the problem?
This evening, my server was hacked, as shown on the screen, followed by my modified home page file. could you tell me how he came in? what is my vulnerability?


Index. php


# Hacked By Ramzi Null #


Body, td, th {
Font-family: Impact;
Font-size: 13px;
Color: #00FF00;
}
Body {
Background-color: #121214;
}
A: link {color: # FFFFFF; text-decoration: none ;}
A: active {color: # FFFFFF; text-decoration: none ;}
A: visited {color: # FFFFFF; text-decoration: none ;}
A: hover {color: #00FF00; text-decoration: none ;}