![]() SQL Injection 3 and 4: URL and POST Injection The following line will let us in: 1' or '1'='1'. Since it expects a string, we need to modify our payload to bypass the login slightly. However, the parameter expects a string instead of an integer, as can be seen here: profileID='10' This challenge uses the same query as in the previous challenge. Since there is no input sanitization, it is possible to bypass the login by using any True condition such as the one below as the ProfileID 1 or 1=1. For this challenge, the parameter accepts an integer, as can be seen here: profileID=10 When logging in, the user supplies input to the profileID parameter. When a user logs in, the application performs the following query: SELECT uid, name, profileID, salary, passportNr, email, nickName, password FROM usertable WHERE profileID=10 AND password = 'ce5ca67.' The safest solution for inline SQL comment is to use - such as - because if it is URL-encoded into - %20- it will still be decoded as. This syntax differs slightly from standard SQL comment syntax, as discussed in Section 1.7.2.4, “‘ - ‘ as the Start of a Comment”. In MySQL, the - (double-dash) comment style requires the second dash to be followed by at least one whitespace or control character (such as a space, tab, newline, and so on). The reason for using - instead of - is primarily because of how MySQL handles the double-dash comment style.įrom a - sequence to the end of the line. Consequently, the attacker bypasses the application’s authentication mechanism and is logged in as the first user returned by the query. If the database executes the SQL statement above, all the users in the users table are returned. SELECT * FROM users WHERE username = '' OR 1=1-' AND password = '' If the attacker enters ‘ OR 1=1 - in the name parameter and leaves the password blank, the query above will result in the following SQL statement. The single quote (‘) in the input is used to close the string literal. In SQL, a string is enclosed within either a single quote (‘) or a double quote (“). The double-dash ( - ) sequence is a comment indicator in SQL and causes the rest of the query to be commented out. Most applications will process the first user returned, meaning that the attacker can exploit this and log in as the first user the query returned. If the attacker supplies the value ‘ OR 1=1 - inside the name parameter, the query might return more than one user. $query = "SELECT * FROM users WHERE username='" + $_POST + "' AND password= '" + $_POST$ + '" " The user and password variables from the POST request is concatenated directly into the SQL statement. The following PHP code demonstrates a dynamic SQL query in a login from. If the application does not sanitize the given input from the attacker-controlled parameter, the query will be vulnerable to SQL injection attack. With control of a parameter, the attacker can inject a malicious query, which will be executed by the database. In other words, the attacker must have access to a parameter that they can control, which goes into the SQL statement. Without input sensitization, the user can make the database interpret the user input as a SQL statement instead of as data. Without checks on the received input, string concatenation becomes the most common mistake that leads to SQL injection vulnerability. ![]() To allow for dynamic SQL queries, developers often concatenate user input directly into the SQL statement. ![]() Our employee management web application has SQL injection vulnerabilities, which mimic the mistakes frequently made by developers.Īpplications will often need dynamic SQL queries to be able to display content based on different conditions set by the user. Through the malicious SQL statements, attackers can steal information from the victim’s database even worse, they may be able to make changes to the database. SQL injection is a technique through which attackers can execute their own malicious SQL statements generally referred to as a malicious payload. Task 2: Introduction to SQL Injection: Part 1
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