Introduction:
SQL injection is a type of security vulnerability that allows an attacker to execute malicious SQL code on a database management system through a web application. This can allow an attacker to gain unauthorized access to sensitive information, modify or delete data, or perform other malicious actions on the database.
SQL injection occurs when user-supplied data is not properly sanitized or validated before being used in a database query. If the user-supplied data is directly included in the query, an attacker can manipulate the data to inject malicious SQL code into the query. The attacker's code is then executed by the database management system, allowing the attacker to carry out malicious actions on the database.
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For this post, I share 3 techniques: how to do SQL injection and after how to easily prevent it.
for more common SQL Injection can you check SQL Injection Cheat Sheet.
NOTE: In this example the code using Hibernate and JDBC Template with MySQL. let go.
Downloading and installing MySQL
docker pull mysql/mysql-server:latest
docker run -d -p 3306:3306 --name mysql-docker-container -e MYSQL_ROOT_PASSWORD=mypass -e MYSQL_DATABASE=test_db -e MYSQL_USER=test -e MYSQL_PASSWORD=test_pass mysql/mysql-server:latest
Script
CREATE TABLE customers ( id BIGINT PRIMARY KEY, name VARCHAR(128), password VARCHAR(128), lastname VARCHAR(128) );INSERT INTO customers (id, name, password, lastname) VALUES (1, 'Henry','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test1'), (2, 'Henry','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test2'), (3, 'Henry','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test3'), (4, 'admin','81dc9bdb52d04dc20036dbd8313ed055', 'test4'), (5, 'User5','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test5'), (6, 'User6','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test6'), (7, 'User7','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test7'), (8, 'User8','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test8'), (9, 'User9', '$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu','test9'), (10, 'User10','$2a$10$iWlXVjsSU9.X0oxEjUwyYe3EOc5X2hqacWY7uuyV0BwonTt5SapSu', 'test10');
Technology
- Spring Boot 3.0.2
- Java 17
- Spring JDBC 6
- Hibernate 6
- Jakarta 3.1
- Docker
- Maven
- IntelliJ IDEA
SQL Injection Attack Samples
Line Comments Sample SQL Injection Attacks
- Spring's JdbcTemplate: Simple query to find By Name And Id, with concat and string replace.
String sql = "SELECT * from customers where name ='"+name+"' AND id="+id; var list = jdbcTemplate.query(sql, (rs, rowNum) -> Customer.builder() .id(rs.getInt("id")) .name(rs.getString("name")) .build() );
If we send these parameters:
var name = "Henry' -- '";
var id = 1;
Should return one record, however return all lists with name are (Henry). because the original query was changed this way [SELECT * from customers where name ='Henry' -- '' AND id=1].
If we use replace, the same thing happens.
String sql = "SELECT * from customers where name =:name AND id=:id";
sql = sql.replace(":name", name).replace(":id",String.valueOf(id));
var list = jdbcTemplate.query(sql, (rs, rowNum) ->
Customer.builder()
.id(rs.getInt("id"))
.name(rs.getString("name"))
.build()
);If we send these parameters:
var name = "'Henry' -- ";
var id = 1;
Should return one record, however return all lists with name are (Henry). because the original query was changed this way [SELECT * from customers where name ='Henry' -- AND id=1].
[
- {
},
- "id":1,
- "name":"Henry"
- {
},
- "id":2,
- "name":"Henry"
- {
}
- "id":3,
- "name":"Henry"
- ...........
- Hibernate 6: Simple query to find By Name And Id, with concat and string replace.
String sql = "SELECT e FROM customers e where name='" + name + "'AND id="+id;
var list = entityManager
.createQuery(sql, Customer.class)
.getResultList();If we send these parameters:
var name = "'Henry' -- ";
var id = 1;
Awesome, Hibernate convert original query this way. Hibernate: select c1_0.id,c1_0.name from customers c1_0 where c1_0.name=('Henry'--'') and c1_0.id=1And return one record. [- {
- "id":1,
- "name":"Henry",
- "password":"124",
- "lastname":"test1"
}
]
If we use replace:String sql = "SELECT e from customers e where name =:name AND lastname =:lastname";
sql = sql.replace(":name", name).replace(":lastname",lastname);
System.out.println(sql);
var list = entityManager
.createQuery(sql, Customer.class)
.getResultList();
If we send these parameters:var name = "'Henry' -- ";
var lastname = "'test1'";
Hibernate convert original query this way: [SELECT e from customers e where name ='Henry' -- AND lastname ='test1']
However Hibernate not permit the query, it will be send next error: org.hibernate.query.sqm.ParsingException
Bypassing Login Screens (SMO+)SQL Injection 101, Login tricks- Spring's JdbcTemplate: Simple query to find By Name And password.
String sql = "SELECT * from customers where name ='"+name+"' AND password='"+password+"'";
var list = jdbcTemplate.query(sql, (rs, rowNum) ->
Customer.builder()
.id(rs.getInt("id"))
.name(rs.getString("name"))
.build()
);
return list;If we send these parameters: (If we use .trim() to remove whitespace, some values in SQL injection don't work. however the good practice is the data should be properly sanitized).
/** No works
Henry' /*
Henry' or 1=1 /*
* */
// SQL injection Ok
//var name = "Henry' -- ";
//var name = "Henry' # ";
//var name = "Henry' or 1=1 -- ";
//var name = "Henry' or 1=1 # ";
var name = "Henry' or '1'='1 --";
var pass = "123";
Should return one record, however return all lists with name are (Henry).
[
- {
- "id":1,
- "name":"Henry"
- {
- "id":2,
- "name":"Henry"
- {
- "id":3,
- "name":"Henry"
- Hibernate 6: Simple query to find By Name And password.
var list = entityManager
.createQuery("SELECT e FROM customers e where name='" + name + "' AND password='"+pass+"'", Customer.class)
.getResultList();If we send these parameters:
/** No works
Henry' --
Henry' #
Henry'/*
Henry' or 1=1 --
Henry' or 1=1 #
Henry' or 1=1 /*
* */
var name = "Henry' or '1'='1 --";
var pass = "123";
Should return one record, however return all lists with name are (Henry).
[- {
- "id":1,
- "name":"Henry"
}, - {
- "id":2,
- "name":"Henry"
}, - {
- "id":3,
- "name":"Henry"
}
]Boolean SQL Injection Attacks
- Spring's JdbcTemplate: Simple query to find By Name.
String sql = "SELECT * from customers where name ='"+name+"'";
var list = jdbcTemplate.query(sql, (rs, rowNum) ->
Customer.builder()
.id(rs.getInt("id"))
.name(rs.getString("name"))
.build()
);
return list;If we send this parameter:
var name = "abc' or '1'='1";
Should not return any record, however return all lists.[
- {
},
- "id":1,
- "name":"Henry"
- {
},
- "id":2,
- "name":"Henry"
- {
}
- "id":3,
- "name":"Henry"
- ...........
- Hibernate: Simple query to find By Name.
var list = entityManager .createQuery("SELECT e FROM customers e where name='" + name + "'", Customer.class) .getResultList();
If we send this parameter:
var name = "abc' or '1'='1";
Should not return any record, however return all lists.[
- {
},
- "id":1,
- "name":"Henry"
- {
},
- "id":2,
- "name":"Henry"
- {
}
- "id":3,
- "name":"Henry"
- ...........
Prevent SQL Injection
- Parameterized queries, also known as prepared statements, use placeholders to represent values in a query. The actual values are then passed as parameters to the query, separately from the SQL code. This makes it much more difficult for an attacker to inject malicious code into a query.
For e.g.
Spring's JdbcTemplate
String sql = "SELECT * from customers where name =? AND id=?";
var list = jdbcTemplate.query(sql, (rs, rowNum) ->
Customer.builder()
.id(rs.getInt("id"))
.name(rs.getString("name"))
.build()
,new Object[]{name, id});
return list; String sql = "SELECT * from customers where name =:name AND id=:id";
MapSqlParameterSource mapSqlParameterSource = new MapSqlParameterSource();
mapSqlParameterSource.addValue("name", name);
mapSqlParameterSource.addValue("id", id);
var list = namedParameterJdbcTemplate.query(sql, mapSqlParameterSource, (rs, rowNum) ->
Customer.builder()
.id(rs.getInt("id"))
.name(rs.getString("name"))
.build()
);
return list;Hibernate 6
var list = entityManager
.createQuery("SELECT e FROM customers e where name=:name AND password=:password", Customer.class)
.setParameter("name", name)
.setParameter("password", pass)
.getResultList();- keep your software up to date to ensure that any security vulnerabilities are patched.
- Consider using a web application firewall (WAF). A WAF or web application firewall helps protect web applications by filtering and monitoring HTTP traffic between a web application and the Internet. It typically protects web applications from attacks such as cross-site forgery, cross-site-scripting (XSS), file inclusion, and SQL injection, among others.
- Use of Properly Constructed Stored Procedures
- Allow-list Input Validation
- For more check SQL Injection Prevention Cheat Sheet.
Test
Spring JDBC main classes:
- BooleanAttacksJDBCTemplate
- BypassingLoginAttacksJDBCTemplate
- LineCommentsAttacksJDBCTemplate
Hibernate 6 main classes:
- BooleanAttacksHibernate
- BypassingLoginAttacksHibernate
- LineCommentsAttacksHibernate
https://www.invicti.com/blog/web-security/sql-injection-cheat-sheet/
https://cheatsheetseries.owasp.org/cheatsheets/SQL_Injection_Prevention_Cheat_Sheet.html
https://www.cloudflare.com/learning/ddos/glossary/web-application-firewall-waf/
