SQL Injections: Introduction, Types, Prevention & Mitigation

You, being the end-user, you may not realize the significance of backend while using any web interface. But, it is the backend only that serves all your queries on Google, cloud all your photos/videos on Instagram and Facebook, let’s you access gaming apps/ websites, etc.

And, while you are enjoying the features of any app, sophisticated processes are being carried out the backend!

Web interfaces are available to everyone. You can’t imagine the amount of work being carried out from your social media interface to CRM.

These apps are a huge business and no doubt why they intrigue cybercriminals. These interfaces are used by the user (customers and employees) to interact with digital systems; web applications signify a large surface for the attack that keeps shaking every organization now and then.

And, if the web interface is poorly coded, it can expose organizations by being the means of conduit to several sensitive data types that include valuable proprietary information and also the personally identifiable data. All this happens because; these web interfaces include an enormous number of third party elements (users) that make them potential security vulnerabilities.

Often, third party technologies are employed to improve functionality and usability, fasten development. Unfortunately, the security factor is either overlooked or poorly managed. The threat to these web interfaces is increasing day by day, which creates a challenging situation for the IT teams.

And, mentioned-below are some type of attacks by which web interfaces should be protected:

  • Technical attacks, e.g., SQL injection, remote file inclusion, and cross-site scripting.
  • Business logic attacks, capable of exploiting faulty logic or standard misuse functionality.
  • Taking over the accounts and fiend force password guessing to do the fraudulent transactions.
  • Botnet-driven that cannot be defended by conventional defense mechanism for DDoS attacks on application-layer.

With other forms of cyberattacks, any kind of breach with a web interface can be very devastating. The ill-consequences can range from the anticipated application downtime and data stealth to damage to the brand and financial losses, quickly adding up to millions of dollars. And the reason here, web application security has shifted from the primary security methods to a critical concern for the owners.

That’s why, as a measure, next-generation web application firewalls (WAFs) are a must-have counteractant that will work beyond the conventional forms of defense that have been relied on in the past. With the beginning of the new digital era, WAF offers the potential that the IT team needs to address the enormous threats that are hovering around. This entails the application inputs validation, jamming automated attacks against business functions, session and cookie protection, etc.

To protect the critically important business resources in an efficient manner, always seek for a WAF that can defend you and your organization against the complicated web attacks and offer flexible protection against the threat, scalability, and flexibility to manage heavier workloads.
Laying a strong base for identifying abnormalities associated with threats that are otherwise hard to recognize, can result in lowering down the threats and work as a strategic solution for protecting all essential web properties of the organization.

 But, if you are seeking the ultimate security system that would help you against the threats for all of your application and data, endpoints, always consider a full-stack solution. Incorporating a next-gen WAF, as well as DDoS protection, zero-day autonomic self-protection, BOT management, and API security, is a way forward.

The landscape of the threats is indeed diverse, complex, and fast-evolving. With the on-premises mobile, cloud, and IoT, you cannot even imagine the bait you are laying out there for the cybercriminals. Only fully-functioning and in-depth strategy can protect your websites, all your applications, networks, and data too.

Here we are going to discuss one thing threat for the databases—SQL Injection.

What is SQL injection?

 It is defined as the vulnerability of web security that enables an attacker to permeate through the system with queries that the application sends to its database. Typically, it allows the intruder to have a view of the data that is not accessible or retrievable to them. This could include anything starting from the user’s personal data, or other data that application is accessing itself. In most of the cases, the intruder enters the system to modify, delete, or to cause any exploitation to the content/behavior of the application.

 In other situations, an attacker shoot-up an SQL injection attack to conciliate with the concerned server or any other backend infrastructure, or carry out a denial-of-service attack.

Types of SQL Injections

Typically, SQL injections are categorized into three categories:
1) The Classic—In-Band SQLi
2) The Blind— Inferential SQLi
3) Out-of-Band SQLi

You can also classify SQL injections depending upon the methods they utilize to access the backend data and the potential of the damage that they cause.

In-band SQLi

For this type of attack, the attacker makes use of the same communication channel to initiate their attacks and wait to collect the results. The efficiency and the simplicity of In-band SQLi make it a common but useful SQLi attack type.

It is sub-categorized into two:

a) Error-based SQLi:  In this method, the attacker performs actions that can trigger the database to generate error messages. And, these error massages serve him leverage of providing data and the information about the database structure that he was yearning for.

b) Union-based SQLi: With this technique, the attacker takes advantage of the UNION SQL operator. This operator is generally used for fusing several ‘select’ statements produced by the database to fetch a single HTTP response. And, the data fetched by this response may leverage the attacker.

Inferential (Blind) SQLi: During this attack method, he sends a part of the data to the server to check and observe the response of the server. He does so because he intends to learn more about the structure of the server. Thus, this method is termed as ‘Blind’ SQLi. As the data is not transferred from the website database to the attacker, he is not allowed to see the information about the in-band attack. These types of SQL injections depend upon the server’s behavioral pattern, so that the server gets typically slower to execute, but of course, these are as harmful as others.

Blind SQL injections can be classified into two categories mentioned below:

a) Boolean: The attacker sends a SQL query to the server that would prompt the application to fetch a result. The result would vary depending upon whether the question is true or false. Then, based on results, the HTTP response will be modified or left unchanged based on the information carried by it. Then, the attacker van makes out if the message generated is either true or false.

b) Time-based: An SQL query is sent to the database by the attacker, making the database wait for a period (second only) before the server reacts in any way. From the time that the database takes to respond, the attacker can make out whether the query holds true or false value. Then, based on the result, an HTTP response will be produced instantly or after the waiting period. Thus, the attacker can take action depending upon the result of the query- true or false.

Out-of-band SQLi: This form of attack can only be carried out by the attacker when certain features, enabled on the server, are used by the web application. This is an alternative to the other two types of attacks—in-band, and inferential SQLi techniques.

It is performed only when the attacker cannot utilize the same channel to initiate the attack and collects the information he wants. It can also be performed when the server is slow or unstable for any actions. These techniques are also used by the attacker based on the capacity of the server to create HTTP/DNS requests to transfer data.

SQLI Prevention and Mitigation

There exist several ways that are effective in preventing SQLi attacks from harming any sensitive data of the organization:

  • The first and foremost thing is to validate (aka sanitization)— a practice of code writing method that can recognize unauthorized user inputs.
  • While you employ validation, always consider the best practice as you would barely find a foolproof solution. In reality, most validation practices it is not feasible to map the inputs and differentiate whether it is legal or illegal. Well, at least, not without cause a plethora of false positives—which in turn hampers the overall user experience and also the functionality of the application.
  • Hence, it is very critical to employ a web application firewall (WAF) that will help out the web application to filter any unauthorized input and recognize if it is an SQLi or any other online threat. A WAF generally relies on the regularly updated list of carefully crafted signatures’ that allows the WAF to weed out the potentially harmful SQL queries or SQLi. And, if we become a little more conscious in employing the right methods, then these SQLi attacks can be stopped for good.