Learn how an attacker can retrieve all user records from a database using a SQL injection attack with the condition “OR ‘z’=’z'”. Understand the risks and protect your web applications.
Table of Contents
Question
A web application receives the following input from a malicious request. What is the attacker attempting to do?
select accountbalance from user where name = jake’ OR ‘z’=’z’;
A. Download database records for a specific application user
B. Combine two input requests into a single query
C. Obtain database records for every application user
D. Add a new user account to the application database
Answer
C. Obtain database records for every application user
Explanation
The attacker is attempting to perform a SQL injection attack to obtain database records for every application user (Answer C).
SQL injection is a technique where malicious SQL statements are inserted into application queries to manipulate the database. In this case, the attacker is exploiting a web application that fails to properly sanitize user input when constructing a SQL query.
The original query likely looks something like this:
select accountbalance from user where name = ‘input_name’;
The intention is for input_name to be replaced by the name submitted by the user, like ‘jake’. However, instead of supplying just a name, the attacker crafted a malicious input:
jake’ OR ‘z’=’z
When this input gets inserted into the query, it becomes:
select accountbalance from user where name = ‘jake’ OR ‘z’=’z’;
The additional OR ‘z’=’z’ condition is always true, since ‘z’ always equals ‘z’. This means the query will return account balances for ALL users, not just the one named jake. The single quote after jake’ closes the quote started before jake, making the rest of the input valid SQL syntax.
To defend against SQL injection attacks like this, it’s crucial to implement proper input validation and parameterized queries. Input validation ensures only expected characters are allowed. Parameterized queries separate the SQL structure from the user-supplied data, preventing it from being interpreted as SQL commands.
In summary, the attacker is using a SQL injection technique with an always-true OR condition in an attempt to trick the database into returning sensitive information (account balances) for every user. This highlights the importance of secure coding practices to protect against such attacks.
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