Whitelists, on the other hand, work particularly well when we can define exactly what is a valid input. A filter’s implementation may vary a lot, but we can generally classify them in two types: whitelists and blacklists.īlacklists, which consist of filters that try to identify an invalid pattern, are usually of little value in the context of SQL Injection prevention – but not for the detection! More on this later. This is the same we’ve done in the plain JDBC case – but with a few statements less, which is nice.Īs a bonus, this approach usually results in a better performing query, since most databases can cache the query plan associated with a prepared statement.ĭata Sanitization is a technique of applying a filter to user supplied-data so it can be safely used by other parts of our application.
#SPRING BOOT SQLITE CODE#
When running this code under Spring Boot, we can set the property to DEBUG and see what query is actually built in order to execute this operation: // Note: Output formatted to fit screenĪs expected, the ORM layer creates a prepared statement using a placeholder for the customerId parameter. Execute query and return mapped results (omitted) TypedQuery q = em.createQuery(jql, Account.class) This interface extends the regular Statement interface with several methods that allow us to safely insert user-supplied values in a query before executing it.įor JPA, we have a similar feature: String jql = "from Account where customerId = :customerId" Here we’ve used the prepareStatement() method available in the Connection instance to get a PreparedStatement. omitted - process rows and return an account list PreparedStatement p = c.prepareStatement(sql) + "customer_id, acc_number, branch_id, balance from Accounts" Let’s rewrite our example function to use this technique: public List safeFindAccountsB圜ustomerId(String customerId) This is very effective and, unless there’s a bug in the JDBC driver’s implementation, immune to exploits. This technique consists of using prepared statements with the question mark placeholder (“?”) in our queries whenever we need to insert a user-supplied value. Nothing bad will happen if we’re sure that this value will only come from trusted sources, but can we? The problem with this code is obvious: we’ve put the customerId‘s value into the query with no validation at all. ResultSet rs = c.createStatement().executeQuery(sql) + "customer_id,acc_number,branch_id,balance "Ĭonnection c = dataSource.getConnection()
UnsafeFindAccountsB圜ustomerId(String customerId)
This statement may sound a bit abstract, so let’s take look at how this happens in practice with a textbook example: public List If in the process of generating this code we use untrusted data without proper sanitization, we leave an open door for hackers to exploit. Injection attacks work because, for many applications, the only way to execute a given computation is to dynamically generate code that is in turn run by another system or component.
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