SQL Injection Attack

A SQL injection is a security attack that is as dangerous as it is ingenious. By abusing the data input mechanisms of an application, an attacker can manipulate the generated SQL query to their advantage, which can cause catastrophic events. 

Many people today might consider SQL injections a thing of the past. In truth, they’re anything but. For instance, 70% of the security exploit attempts on Rails apps analyzed in Sqreen’s State of Application Security Report were SQL injections. This finding shows that even a robust framework such as Ruby on Rails—which counts as a tried and true ORM in the form of Active Record—is not a silver bullet when it comes to SQL injections. SQL injection is still top of the list of most common security threats to web apps, and it has been there for quite a while. 

What are organizations supposed to do to avoid this problem, then? Education is the key. And that’s what this post is about: educating people about not only what SQL injections are and how they work, but most importantly how to avoid them. Let’s dig in. 

What is SQL Injection Attack?

Structured Query Language (SQL) is a language designed to manipulate and manage data in a database. SQL injection (SQLi) is a web security vulnerability that allows an attacker to interfere with the queries that an application makes to its database. It generally allows an attacker to view data that they are not normally able to retrieve.This might include data belonging to other users, or any other data that the application itself is able to access. In many cases, an attacker can modify or delete this data, causing persistent changes to the application's content or behavior. Since its inception, SQL has steadily found its way into many commercial and open-source databases. SQL injection (SQLi) is a type of cybersecurity attack that targets these databases using specifically crafted SQL statements to trick the systems into doing unexpected and undesired things.

Why are SQL injections so dangerous?

Some might think that a SQL injection is only really damaging when the attacker gets write privileges to the database. 

That couldn’t be further from the truth. 

An attacker who reads unauthorized information alone can give you a lot of headaches. The attacker could access and expose sensitive data like financial data and personal information. Besides tarnishing your organization’s reputation, such a leak would cause consequences to your users/customers as the data is shared and sold. It could also put you in trouble with privacy regulations such as Europe’s GDPR or California’s CCPA, which could lead to severe legal and financial consequences. 

How do SQL injection attacks work?

Most applications allow their users to input data somehow, and web applications are no different. Malicious individuals can abuse those data-entering mechanisms in ways that interfere with the generation of SQL queries. 

The things I call “data entering mechanisms” are the ways by which users input data into the application. Most of the time, these would be form fields and URL parameters. By tinkering with those elements in just the right way, attackers can inject—hence the name—additional SQL commands, which get executed. 

Types of SQL Injection Attack

SQL injection attacks can be carried out in a number of ways. Attackers may observe a system’s behavior before selecting a particular attack vector/method.

Unsanitized Input

Unsanitized input is a common type of SQLi attack in which the attacker provides user input that isn’t properly sanitized for characters that should be escaped, and/or the input isn’t validated to be the type that is correct/expected. 

For example, a website used to pay bills online might request the user’s account number in a web form and then send that to the database to pull up the associated account information. If the web application is building a SQL query string dynamically with the account number the user provided, it might look something like this:

            “SELECT * FROM customers WHERE account = ‘“+ userProvidedAccountNumber +”’;”

While this works for users who are properly entering their account number, it leaves the door open for attackers. For example, if someone decided to provide an account number of “‘ or ‘1’ = ‘1”, that would result in a query string of:

            “SELECT * FROM customers WHERE account = ‘’ or ‘1’ = ‘1’;”

Due to the ‘1’ = ‘1’ always evaluating to TRUE, sending this statement to the database will result in the data for all customers being returned instead of just a single customer.

Blind SQL Injection

Also referred to as Inferential SQL Injection, a Blind SQL injection attack doesn’t reveal data directly from the database being targeted. Rather, the attacker closely examines indirect clues in behavior. Details within HTTP responses, blank web pages for certain user input, and how long it takes the database to respond to certain user input are all things that can be clues depending on the goal of the attacker. They could also point to another SQLi attack avenue for the attacker to try.

Out-of-Band Injection

This attack is a bit more complex and may be used by an attacker when they cannot achieve their goal in a single, direct query-response attack. Typically, an attacker will craft SQL statements that, when presented to the database, will trigger the database system to create a connection to an external server the attacker controls. In this fashion, the attacker can harvest data or potentially control behavior of the database.

A Second Order Injection is a type of Out-of-Band Injection attack. In this case, the attacker will provide an SQL injection that will get stored and executed by a separate behavior of the database system. When the secondary system behavior occurs (it could be something like a time-based job or something triggered by other typical admin or user use of the database) and the attacker’s SQL injection is executed, that’s when the “reach out” to a system the attacker controls happens.

A SQL injection example

Imagine a real estate agency website. After accessing the site, you can search for different kinds of properties and further filter by “renting” or “buying.” Typical stuff. After selecting your search parameters and clicking on the Search button, the selected parameters get added as URL parameters. So, let’s say you’re searching for apartments. Your URL would look something like this: 

https://fakerealestate.com/properties?category=Apartments

And the resulting SQL query that gets sent to the database would be something like this: 

SELECT * FROM properties WHERE category = 'Apartments'

The query above is pretty straightforward. We want to retrieve the rows from the properties table in which the value of the category column is equal to Apartments. 

For the sake of the argument, let’s say this site is vulnerable to SQL injections. Let’s see what would happen if someone changed the URL to this: 

https://fakerealestate.com/properties?category=Apartments’+OR+1=1–

That would effectively result in the following query: 

SELECT * FROM properties WHERE category = 'Apartments' OR 1 = 1

Since one always equals one, the query above successfully asks the database for properties from all categories. This is a harmless example, but the general modus operandi is the same: The attacker wants to conclude the legitimate query and inject more commands after it in order to gain access to something they’re not supposed to be able to access, such as a list of all users and passwords.  

How to Prevent SQL Injection Attacks?

Preventing or mitigating SQL injection attacks is a lot about ensuring that none of the fields are vulnerable to invalid inputs and application execution. yours is manually impossible to actually to check every page and every application on the website, especially when updates are frequent and user-friendliness is the top priority. Nonetheless, security analysts and seasoned developers recommend a number of the subsequent points guarantee your database square measure well protected inside the confinement of the server.

1) Continuous Scanning and Penetration Testing

The automated web application scanner has been the best choice to point out vulnerabilities within the web applications for quite some time now. Now, with SQL injections getting smarter in exploiting logical flaws, website security professionals should explore manual testing with the help of a security vendor.

They can authenticate user inputs against a set of rules for syntax, type, and length. It helps to audit application vulnerabilities discreetly so that you can patch the code before hackers exploit it to their advantage.

2) Restrict Privileges

It is more of a database management function, but enforcing specific privileges to specific accounts helps prevent blind SQL injection attacks. Begin with no privileges account and move on to ‘read-only’, ‘edit’, ‘delete’ and similar privilege levels.

Minimizing privileges to the application will ensure that the attacker, who gets into the database through the application, cannot make unauthorized use of specific data.

3) Use Query Parameters

Dynamic queries create a lot of troubles for security professionals. They have to deal with variable vulnerabilities in each application, which only gets graver with updates and changes. It is recommended that you prepare parameterized queries.

These queries are simple, easy to write, and only pass when each parameter in SQL code is clearly defined. This way, your info is supplied with weapons to differentiate between code and information inputs.

4) Instant Protection

A majority of organizations fail the problems like outdated code, scarcity of resources to test and make changes, no knowledge of application security, and frequent updates in the application. For these, web application protection is the best solution.

A managed web application firewall can be deployed for immediate mitigation of such attacks. It contains custom policies to block any suspicious input and deny information breaches instantly. This way, you do not have to manually look for loopholes and mend problems afterward.

Published By:

Yashashree Shastri

Syeda Zarah Aiman

Rutuja Rathi

Vaishnav Suryawanshi