![]() Many database engines also provide the functionality to execute commands in the operating system from SQL. But it might not be as difficult as you think… I’ll post another article about how you can manage to get information about the query being executed later. Of course an attacker will need to know which kind of statements are executed by your software in order to exploit such a security hole. You also need to make sure the encrypted data cannot be accessed that easily. I do hope the passwords will be at least encrypted but encryption alone is not always enough to protect data. If the attacker now sends the following as order_id, he will get a list of all users and their passwords: 1 UNION SELECT name, password FROM users Let’s say you have an order table and you can call the server to display all items in a particular order with such a statement: $statement = "SELECT name, value FROM items WHERE order_id=".$order_id the data from both table are displayed in the table on the client.you inject a UNION clause to fetch data from another table.the server you are attacking is fetching data using a query and displaying this data in a tabular form.This is usually done using a kind of UNION injection. But it you used PostgreSQL instead of MySQL it would be possible.Īnother thing which is often done using SQL injection is getting access to data in the database which should be protected. The execution will fail since you can only have one statement executed at a time. Fortunately, when using PHP and MySQL these kind of batched queries are not supported. The first statement will be executed normally and the drop table will then be executed additionally. ![]() using a user name like: admin' DROP TABLE important_table. ![]() closing the first query and having a second query executed which would either return sensitive information or destroying something e.g. This is typically done by using batched queries i.e. It can be used to perform actions which are not intended to be allowed. Let’s say you statement now looks like this: SELECT password FROM user WHERE user_name='xxx'Īll the attacker has to do is to use the following username: admin' AND 1=0 UNION SELECT 'known_md5_checksumīut SQL injection is not only used to be able to login without credential. Unfortunately, it is also trivial to workaround such security fixes. The double dash would make the rest of the line a comment and the statement would always return 1 allowing the attacker to login as admin without valid credentials.Īn easy fix for this security issue is not to return 1 but to return an MD5 of the password and compare it with the password provided. ![]() The generated SQL query would be: SELECT 1 FROM users WHERE user_id='admin' -' AND password='anything' ![]() If you take the parameters and built an SQL statement like this: $query = "SELECT 1 FROM users WHERE user_id='".$user_name."' AND password='".$password"'" Let’s say you have a very poorly programmed login function which is called with two parameter, a user name and a password. SQL injection means that an attacker is injecting some pieces of SQL code in a call to a server instead of just sending some text information in order to go around security mechanisms or in order to perform something which shouldn’t be allowed. First let’s have a look at what SQL injection is about. ![]()
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