Prevention of SQL injection attacks in the application headers
# Controller
class ClientsController < ApplicationController
def show
idClient = request.headers['idClient']
@client = Client.find_by_sql("SELECT * FROM clients WHERE id = #{idClient}")
end
end
In this code snippet, we have a Ruby on Rails controller named
ClientsController
which handles operations related to
Client
objects. One of the operations is
show
which is used to retrieve a specific client's details.
The
show
method retrieves the
idClient
from the headers of the HTTP request. This
idClient
is then directly used in a SQL query to fetch the client's details from the database. The SQL query is constructed as a string with the
idClient
value embedded in it.
The problem with this approach is that it leaves the application vulnerable to SQL Injection attacks. If an attacker sends a specially crafted
idClient
value in the request headers, they could manipulate the SQL query to retrieve unauthorized data or perform other malicious operations. This is because the
idClient
value is directly interpolated into the SQL query string without any sanitization or escaping.
For example, if an attacker sends
1 OR 1=1
as the
idClient
, the SQL query becomes
SELECT * FROM clients WHERE id = 1 OR 1=1
which would return all clients instead of just one, thus causing a data leak.
# Controller
class ClientsController < ApplicationController
def show
idClient = request.headers['idClient']
@client = Client.where("id = ?", idClient).first
end
end
The original code was vulnerable to SQL Injection through the 'idClient' header. The 'idClient' value was directly interpolated into the SQL query, which means that an attacker could potentially manipulate the SQL query by sending a specially crafted 'idClient' value.
The fixed code uses the ActiveRecord
where
method to query the database. This method automatically escapes the input parameters, preventing SQL Injection attacks. The
where
method takes two arguments: the SQL fragment and the value to substitute into the SQL fragment. The '?' in the SQL fragment is a placeholder that gets replaced with the sanitized 'idClient' value.
The
first
method is used to return the first record that matches the condition. If no record matches the condition,
nil
is returned. This is a safer alternative to
find_by_sql
, which executes a raw SQL query and is therefore more susceptible to SQL Injection attacks.
This fix ensures that the application is no longer vulnerable to SQL Injection attacks through the 'idClient' header. However, it's important to apply the same principles to all parts of the application that interact with the database. Always use parameterized queries or the ORM's methods to interact with the database, and never concatenate user input directly into SQL queries.